Tokushima University / Educator and Researcher Directory --- Nagamatsu, Kentaro

Personal Web Page

https://researchmap.jp/nagamatsukentaro (researchmap)

Field of Study

○	Electrical and Electronic Engineering

Subject of Study

○	電子・電気材料工学 (nitride semiconductor, light emitting diode, laser diode, transistor, process)

Book / Paper

Academic Paper (Judged Full Paper):

1.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Dynamic wide gamut color generation using highly lossy metal-based metal-dielectric-metal structure, Applied Physics Express, Vol.17, No.7, 072005-1-072005-5, 2024. (Keyword) nanophotonics (Tokushima University Institutional Repository) ● Metadata: 119535 (Link to Publication Site) ● Publication site (DOI): 10.35848/1882-0786/ad62d3 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.35848/1882-0786/ad62d3 (Tokushima University Institutional Repository: 119535, DOI: 10.35848/1882-0786/ad62d3)
2.	Yuusuke Takashima, Shunsuke Furuta, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Broadband Ag/SiO2/Fe/TiO2 ultrathin planar absorber with a wide acceptance angle from visible to near-infrared regions, Optical Materials Express, Vol.14, No.3, 778-791, 2024. (Keyword) nanophotonics / electrical and electronic materials (Tokushima University Institutional Repository) ● Metadata: 119044 (Link to Publication Site) ● Publication site (DOI): 10.1364/OME.517239 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1364/OME.517239 (Tokushima University Institutional Repository: 119044, DOI: 10.1364/OME.517239)
3.	Tomita Atsushi, Miyagawa Takumi, Hirayama Hideki, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : Investigation of V/III ratio dependencies for optimizing AlN growth during reduced parasitic reaction in metalorganic vapor phase epitaxy., Scientific Reports, Vol.13, 3308.1-7, 2023. (Tokushima University Institutional Repository) ● Metadata: 119114 (Link to Publication Site) ● Publication site (DOI): 10.1038/s41598-023-30489-z (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1038/s41598-023-30489-z (Tokushima University Institutional Repository: 119114, DOI: 10.1038/s41598-023-30489-z)
4.	Kentaro Nagamatsu, Miyagawa Takumi, Tomita Atsushi, Hirayama Hideki, Yuusuke Takashima and Yoshiki Naoi : High growth temperature for AlN by jet stream gas flow metalorganic vapor phase epitaxy., Scientific Reports, Vol.13, 2438, 2023. (Tokushima University Institutional Repository) ● Metadata: 119075 (Link to Publication Site) ● Publication site (DOI): 10.1038/s41598-023-29150-6 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1038/s41598-023-29150-6 (Tokushima University Institutional Repository: 119075, DOI: 10.1038/s41598-023-29150-6)
5.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Ultra-thin deep ultraviolet perfect absorber using an Al/TiO₂/AlN system, Optics Express, Vol.30, No.24, 44229-44239, 2022. (Keyword) nanophotonics (Tokushima University Institutional Repository) ● Metadata: 117757 (Link to Publication Site) ● Publication site (DOI): 10.1364/OE.474847 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1364/OE.474847 (Tokushima University Institutional Repository: 117757, DOI: 10.1364/OE.474847)
6.	Takaaki Koma, Naoya Doi, Akihiro Suzuki, Kentaro Nagamatsu, Takeshi Yasui, Koji Yasutomo, Akio Adachi, Takeo Minamikawa and Masako Nomaguchi : Major target for UV-induced complete loss of HIV-1 infectivity: A model study of single-stranded RNA enveloped viruses, Frontiers in Virology, Vol.2, 994842, 2022. (Link to Publication Site) ● Publication site (DOI): 10.3389/fviro.2022.994842 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.3389/fviro.2022.994842 (DOI: 10.3389/fviro.2022.994842)
7.	Kentaro Nagamatsu, Shota Tsuda, Takumi Miyagawa, Reiya Aono, Hideki Hirayama, Yuusuke Takashima and Yoshiki Naoi : Reduction of parasitic reaction in high temperature AlN growth by jet stream gas flow metal organic vapor phase epitaxy, Scientific Reports, Vol.12, 7662, 2022. (Tokushima University Institutional Repository) ● Metadata: 117388 (Link to Publication Site) ● Publication site (DOI): 10.1038/s41598-022-10937-y (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1038/s41598-022-10937-y (Tokushima University Institutional Repository: 117388, DOI: 10.1038/s41598-022-10937-y)
8.	Akihiro Suzuki, Akira Emoto, Akihiro Shirai and Kentaro Nagamatsu : Ultraviolet Light-Emitting Diode (UV-LED) Sterilization of Citrus Bacterial Canker Disease Targeted for Effective Decontamination of Citrus Sudachi Fruit, Biocontrol Science, Vol.27, No.1, 1-7, 2022. (Link to Publication Site) ● Publication site (DOI): 10.4265/bio.27.1 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.4265/bio.27.1 (DOI: 10.4265/bio.27.1)
9.	Yuusuke Takashima, Atsuki Sasada, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Design of AlN-subwavelength grating for deep ultraviolet wavelength reflector operating at 244 nm of wavelength, Proceedings of SPIE, Vol.11926, 1192618-1-1192618-4, 2021. (Tokushima University Institutional Repository) ● Metadata: 116674 (Link to Publication Site) ● Publication site (DOI): 10.1117/12.2616175 (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-85120469004 (Tokushima University Institutional Repository: 116674, DOI: 10.1117/12.2616175, Elsevier: Scopus)
10.	Takeo Minamikawa, Takaaki Koma, Akihiro Suzuki, Takahiko Mizuno, Kentaro Nagamatsu, Hideki Arimochi, Koichiro Tsuchiya, Kaoru Matsuoka, Takeshi Yasui, Koji Yasutomo and Masako Nomaguchi : Quantitative evaluation of SARS-CoV-2 inactivation using a deep ultraviolet light-emitting diode., Scientific Reports, Vol.11, 5070, 2021. (Summary) for 300 nm are required to inactivate 99.9% of SARS-CoV-2. Our results provide quantitative antiviral effects of DUV irradiation on SARS-CoV-2, serving as basic knowledge of inactivation technologies against SARS-CoV-2. (Tokushima University Institutional Repository) ● Metadata: 117265 (Link to Publication Site) ● Publication site (DOI): 10.1038/s41598-021-84592-0 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33658595 ● Search Scopus @ Elsevier (PMID): 33658595 ● Search Scopus @ Elsevier (DOI): 10.1038/s41598-021-84592-0 (Tokushima University Institutional Repository: 117265, DOI: 10.1038/s41598-021-84592-0, PubMed: 33658595)
11.	Yuto Ando, Kentaro Nagamatsu, Manato Deki, Noriyuki Taoka, Atsushi Tanaka, Shugo Nitta, Yoshio Honda, Tohru Nakamura and Hiroshi Amano : Electrical properties of GaN metal-insulator-semiconductor field-effect transistors with Al2O3/GaN interfaces formed on vicinal Ga-polar and nonpolar surfaces, Applied Physics Letters, Vol.117, No.242104, 2020. (Link to Publication Site) ● Publication site (DOI): 10.1063/5.0028516 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1063/5.0028516 (DOI: 10.1063/5.0028516)
12.	Yuto Ando, Kentaro Nagamatsu, Manato Deki, Noriyuki Taoka, Atsushi Tanaka, Shugo Nitta, Yoshio Honda, Tohru Nakamura and Hiroshi Amano : Low interface state densities at Al2O3/GaN interfaces formed on vicinal polar and non-polar surfaces, Applied Physics Letters, Vol.117, No.102102, 2020. (Link to Publication Site) ● Publication site (DOI): 10.1063/5.0010774 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1063/5.0010774 (DOI: 10.1063/5.0010774)
13.	Tanaka Atsushi, Kentaro Nagamatsu, Usami Shigeyoshi, Kushimoto Maki, Deki Manato, Nitta Shugo, Honda Yoshio, Bockowski Michal and Amano Hiroshi : V-shaped dislocations in a GaN epitaxial layer on GaN substrate, AIP Advances, Vol.9, No.9, 2019. (Summary) In this study, V-shaped dislocations in a GaN epitaxial layer on a free-standing GaN substrate were observed. Our investigation further revealed that the V-shaped dislocations were newly generated at the interface in the epilayer rather than propagated from the GaN substrate. V-shaped dislocations consist of two straight parts. The straight parts of the V-shaped dislocations were separated from each other in the m-direction and tilted toward the step-flow direction of the GaN epitaxial layer. The V-shaped dislocations are continuous single dislocations having a Burgers vector component of 1a and an intrinsic stacking fault between their straight parts. (Tokushima University Institutional Repository) ● Metadata: 114980 (Link to Publication Site) ● Publication site (DOI): 10.1063/1.5114866 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1063/1.5114866 (Tokushima University Institutional Repository: 114980, DOI: 10.1063/1.5114866)
14.	Z. Ye, S. Nitta, Kentaro Nagamatsu, N. Fujimoto, M. Kushimoto, M. Deki, A. Tanaka, Y. Honda, M. Pristovsek and H. Amano : Ammonia decomposition and reaction by high-resolution mass spectrometry for group III Nitride epitaxial growth, Journal of Crystal Growth, Vol.516, 63-66, 2019. (Summary) The decomposition of ammonia (NH3) in nitrogen (N2) ambient was studied under non-equilibrium conditions similar to those in a metal organic vapor phase epitaxy (MOVPE) reactor during the epitaxial growth of group-III nitrides. The gas phase was sampled at different positions and analyzed using a time-of-flight mass spectrometry system with a high resolution (better than 0.002u). Our results expand earlier findings. Even at the high temperature of 1200°C, only 26% of NH3 decomposed in a clean metal-free reactor, whereas a higher ratio of NH3 decomposition was realized in the presence of stainless steel. The activation energy in the clean reactor was calculated to be 0.965±0.004eV. These results demonstrate the capability of our setup and shed new light on the elucidation of the vapor phase growth mechanism of group III-nitrides by MOVPE. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2019.03.025 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2019.03.025 (DOI: 10.1016/j.jcrysgro.2019.03.025)
15.	Kentaro Nagamatsu, Y. Ando, T. Kono, H. Cheong, S. Nitta, Y. Honda, M. Pristovsek and H. Amano : Effect of substrate misorientation on the concentration of impurities and surface morphology of an epitaxial GaN layer on N-polar GaN substrate by MOVPE, Journal of Crystal Growth, Vol.512, 78-83, 2019. (Summary) This study examines the effect of (0001) GaN substrate misorientation on the residual impurities and surface morphology of N-polar GaN grown by metalorganic vapor-phase epitaxy. Carbon, silicon, and oxygen concentrations decreased with increasing GaN substrate misorientation angle, with the lowest impurity concentration achieved for a misorientation angle of 2° toward the m-axis, with 6×1015cm3 carbon, 6×1015cm3 silicon, and 4×1017cm3 oxygen atoms. The oxygen concentration was measured at a depth of 0.5μm below the wafer surface, and the oxygen concentration decreased with increasing thickness. The incorporation of carbon and oxygen revealed a strong dependence on the misorientation angle. The step distance height of the steps parallel to the [1120] direction (or perpendicular to the [1100] m-direction) was confirmed to be a double-height layer step. This phenomenon indicated that m-direction steps are stable for N-polar growth in GaN. In cases of large misorientation toward the m-axis in of the GaN substrate it was difficult to control the misorientation perpendicular to the nominal direction leading to a-axis direction by wafer bowing at wafer manufacturing. Therefore, step-bunching was generated for each symmetric m-axis due to an increase in the compound's off-angle, thus causing the surface roughness to become large. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2019.02.013 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2019.02.013 (DOI: 10.1016/j.jcrysgro.2019.02.013)
16.	K. Uesugi, Y. Hayashi, K. Shojiki, S. Xiao, Kentaro Nagamatsu, H. Yoshida and H. Miyake : Fabrication of AlN templates on SiC substrates by sputtering-deposition and high-temperature annealing, Journal of Crystal Growth, Vol.510, 13-17, 2019. (Summary) High-quality AlN templates fabricated by sputtering-deposition and post-deposition high-temperature annealing have great potential for deep ultraviolet light-emitting device applications. In this work, we fabricated AlN films on 6H-SiC substrates by sputtering and face-to-face annealing and characterized the structural quality of the AlN films before and after annealing. As reported in previous studies, to accomplish high-quality AlN films on SiC substrates using conventional methods, such as molecular beam epitaxy or metalorganic vapor phase epitaxy (MOVPE), it is important to grow the AlN on the SiC coherently. However, in this work, although the annealed AlN films were fully relaxed from the SiC substrates, or even had tensile strain, the AlN films indicated high crystallinity. The X-ray rocking curve full width at half maximum (XRC-FWHM) values of the 200-nm-thick annealed AlN film were 17 and 246arcsec for the AlN (0002) and (1012) diffraction, respectively. Though the annealed AlN film indicated rough surfaces with bunched step structures, the surface morphology was remarkably improved by MOVPE growth and clear atomic step-and-terrace structures were formed. The XRC-FWHM values of the MOVPE-grown AlN were 90 and 239arcsec for the AlN (0002) and (1012) diffraction, respectively. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2019.01.011 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2019.01.011 (DOI: 10.1016/j.jcrysgro.2019.01.011)
17.	Kentaro Nagamatsu, Xiaotong Liu, Kenjiro Uesugi and Hideto Miyake : Improved emission intensity of UVC-LEDs from using strain relaxation layer on sputter-annealed AlN, Japanese Journal of Applied Physics, Vol.58, No.SC, SCCC07, 2019. (Summary) This study examines the effect of (0001) GaN substrate misorientation on the residual impurities and surface morphology of N-polar GaN grown by metalorganic vapor-phase epitaxy. Carbon, silicon, and oxygen concentrations decreased with increasing GaN substrate misorientation angle, with the lowest impurity concentration achieved for a misorientation angle of 2° toward the m-axis, with 6×1015cm3 carbon, 6×1015cm3 silicon, and 4×1017cm3 oxygen atoms. The oxygen concentration was measured at a depth of 0.5μm below the wafer surface, and the oxygen concentration decreased with increasing thickness. The incorporation of carbon and oxygen revealed a strong dependence on the misorientation angle. The step distance height of the steps parallel to the [1120] direction (or perpendicular to the [1100] m-direction) was confirmed to be a double-height layer step. This phenomenon indicated that m-direction steps are stable for N-polar growth in GaN. In cases of large misorientation toward the m-axis in of the GaN substrate it was difficult to control the misorientation perpendicular to the nominal direction leading to a-axis direction by wafer bowing at wafer manufacturing. Therefore, step-bunching was generated for each symmetric m-axis due to an increase in the compound's off-angle, thus causing the surface roughness to become large. (Link to Publication Site) ● Publication site (DOI): 10.7567/1347-4065/ab07a1 (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-85070757794 (DOI: 10.7567/1347-4065/ab07a1, Elsevier: Scopus)
18.	Kentaro Nagamatsu, Y. Ando, Z. Ye, O. Barry, A. Tanaka, M. Deki, S. Nitta, Y. Honda, M. Pristovsek and H. Amano : Comparing high-purity c- and m-plane GaN layers for Schottky barrier diodes grown homoepitaxially by metalorganic vapor phase epitaxy, Japanese Journal of Applied Physics, Vol.57, No.10, 105501, 2018. (Summary) GaN vertical Schottky barrier diodes (SBDs) were grown on m-plane GaN substrates by metalorganic vapor phase epitaxy (MOVPE) using a quartz-free flow channel (FC). The use of the quartz-free FC reduced the impurity concentrations of silicon and carbon by factors of 2 and 10, respectively, compared with the concentrations obtained using a conventional reactor with a quartz FC. The oxygen concentration was found to decrease with increasing the layer thickness. We achieved the same impurity concentration for the epitaxial layers grown on m-plane GaN substrates as for those grown on c-plane GaN substrates under the same growth conditions. A high resistivity of unintentionally doped GaN was achieved by decreasing the impurity concentration. Additionally, for the further understanding of the low impurity concentration in the m-plane GaN, the n-type GaN was inserted between the m-plane GaN substrate and the drift layer. The results revealed that the c- and m-plane breakdown voltages and leakage currents have similar tendencies. (Link to Publication Site) ● Publication site (DOI): 10.7567/JJAP.57.105501 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.7567/JJAP.57.105501 (DOI: 10.7567/JJAP.57.105501)
19.	X. Yang, S. Nitta, M. Pristovsek, Y. Liu, Kentaro Nagamatsu, M. Kushimoto, Y. Honda and H. Amano : Interface amorphization in hexagonal boron nitride films on sapphire substrate grown by metalorganic vapor phase epitaxy, Applied Physics Express, Vol.11, No.5, 051002, 2018. (Summary) Hexagonal boron nitride (h-BN) films directly grown on c-plane sapphire substrates by pulsed-mode metalorganic vapor phase epitaxy exhibit an interlayer for growth temperatures above 1200 °C. Cross-sectional transmission electron microscopy shows that this interlayer is amorphous, while the crystalline h-BN layer above has a distinct orientational relationship with the sapphire substrate. Electron energy loss spectroscopy shows the energy-loss peaks of B and N in both the amorphous interlayer and the overlying crystalline h-BN layer, while Al and O signals are also seen in the amorphous interlayer. Thus, the interlayer forms during h-BN growth through the decomposition of the sapphire at elevated temperatures. (Link to Publication Site) ● Publication site (DOI): 10.7567/APEX.11.051002 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.7567/APEX.11.051002 (DOI: 10.7567/APEX.11.051002)
20.	Noriko Usami, Y. Ando, A. Tanaka, Kentaro Nagamatsu, M. Deki, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Correlation between dislocation and leakage current of p-n diodes on free standing GaN substrate, Applied Physics Letters, Vol.112, No.18, 182106, 2018. (Summary) Dislocations that cause a reverse leakage current in vertical p-n diodes on a GaN free-standing substrate were investigated. Under a high reverse bias, dot-like leakage spots were observed using an emission microscope. Subsequent cathodoluminescence (CL) observations revealed that the leakage spots coincided with part of the CL dark spots, indicating that some types of dislocation cause reverse leakage. When etch pits were formed on the dislocations by KOH etching, three sizes of etch pits were obtained (large, medium, and small). Among these etch pits, only the medium pits coincided with leakage spots. Additionally, transmission electron microscopy observations revealed that pure screw dislocations are present under the leakage spots. The results revealed that 1c pure screw dislocations are related to the reverse leakage in vertical p-n diodes. (Link to Publication Site) ● Publication site (DOI): 10.1063/1.5024704 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1063/1.5024704 (DOI: 10.1063/1.5024704)
21.	X. Yang, S. Nitta, Kentaro Nagamatsu, S. Bae, H. Lee, Y. Liu, M. Pristovsek, Y. Honda and H. Amano : Growth of hexagonal boron nitride on sapphire substrate by pulsed-mode metal-organic vapor phase epitaxy, Journal of Crystal Growth, Vol.482, 1-8, 2018. (Summary) Hexagonal boron nitride (h-BN) was directly grown on sapphire substrate using alternating ammonia (NH3) and triethylboron (TEB) supply (pulsed mode) in metalorganic vapor phase epitaxy. The best condition is when just enough NH3 is supplied to fully convert the TEB within one cycle. Excess NH3 caused islands on h-BN film surface while a lack of NH3 does not form h-BN at all. The epitaxial relationship between grown h-BN layer and c-plane sapphire was confirmed to be [0001]h-BN[0001]sapphire and [10-10]h-BN[11-20]sapphire. It is known that, compared to AlN, BN requires higher V/III ratios for good crystallinity, which due to severe gas-phase reactions is difficult to achieve using continuous supply. Thus using pulsed mode the FWHM of the symmetric (0002) diffraction was almost halved and the growth rate was several times faster. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2017.10.036 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2017.10.036 (DOI: 10.1016/j.jcrysgro.2017.10.036)
22.	A. Tanaka, Y. Ando, Kentaro Nagamatsu, M. Deki, H. Cheong, B. Ousmane, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : m-Plane GaN Schottky barrier diodes fabricated with MOVPE layer on several off-angled m-plane GaN substrate, Physica Status Solidi (A) Applications and Materials Science, Vol.215, No.9, 1700645, 2017. (Summary) In this study, GaN mplane Schottky barrier diodes are fabricated by metalorganic vaporphase epitaxy (MOVPE) on several offangle gallium nitride (GaN) substrates, and the offcut angle dependence of impurity incorporation is investigated. We show that the MOVPE layer on the substrate inclined 5° toward the [0001] direction has extremely low impurity incorporation. These results provide important suggestions for the fabrication of mplane power devices. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.201700645 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.201700645 (DOI: 10.1002/pssa.201700645)
23.	A. Tanaka, O1. Barry, Kentaro Nagamatsu, J. Matsushita, M. Deki, Y. Ando, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Facet dependence of leakage current and carrier concentration in m-plane GaN Schottky barrier diode fabricated with MOVPE, Physica Status Solidi (A) Applications and Materials Science, Vol.214, No.8, 1770150, 2017. (Summary) The background of this cover page shows a superimposed emission microscope image observed from backside of a GaN mplane Schottky barrier diode with reverse biased condition. It can be observed that the epitaxial layer of mplane GaN has pyramidal hillocks at the surface, and only facets inclined toward the [0001] direction (+c facet) have emission due to leakage current. Three images at the corner are differential interference contrast microscopy image (upper left), photoluminescence intensity mapping image (PL, upper right), and cathode luminescence image (CL, lower left), respectively, observing the same pyramidal hillocks to investigate the characteristics of each facet. The PL image indicates the intensity of nearbandedge emission (around 363 nm wavelength) of the facets. Details are discussed in the article by Tanaka et al. (no. 1600829). The +c facets have high emission intensity, indicating that there is a high impurity concentration in the +c facets. Furthermore, we consider this is the reason that +c facets have high leakage current. The CL image is a panchromatic image, and facets inclined toward [0001] direction (c facet) have lowest emission. Together with PL intensity mapping it can be considered that c facets have less yellow emission and less impurity concentration. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.201770150 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.201770150 (DOI: 10.1002/pssa.201770150)
24.	A. Tanaka, O1. Barry, Kentaro Nagamatsu, J. Matsushita, M. Deki, Y. Ando, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Facet dependence of leakage current and carrier concentration in m-plane GaN Schottky barrier diode fabricated with MOVPE, Physica Status Solidi (A) Applications and Materials Science, Vol.214, No.8, 1600829, 2017. (Summary) In this study, GaN mplane Schottky barrier diodes fabricated with a metalorganic vaporphase epitaxy on a GaN substrate were investigated using emission microscope, photoluminescence, and cathodoluminescence. In addition, facet dependence of leakage current under reversebiased condition was observed. We showed that the leakagecurrent distribution was caused by the facet dependence of the carrier concentration and oxygen concentration. These results can provide important suggestions for the fabrication of mplane devices. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.201600829 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.201600829 (DOI: 10.1002/pssa.201600829)
25.	Kentaro Nagamatsu, S. Nitta, Z. Ye, H. Nagao, S. Miki, Y. Honda and H. Amano : Decomposition of trimethylgalliumand adduct formation in a metalorganic vapor phase epitaxy reactor analyzed by high-resolution gas monitoring system, Physica Status Solidi (B) Basic Solid State Physics : PSS, Vol.254, No.8, 1600737, 2017. (Summary) In this study, by using timeofflight (TOF) highresolution and highsensitivity mass spectrometry measurements, the decomposition of trimethylgallium into dimethylgallium and monomethylgallium along with its adduct formation with NHx in a commercially available horizontal metalorganic vaporphase epitaxy (MOVPE) reactor with a resistive heater was investigated and observed in more detail than previously reported. The results confirmed the use of the TOF monitoring system in analyzing the elementary reaction process in actual MOVPE systems. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssb.201600737 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssb.201600737 (DOI: 10.1002/pssb.201600737)
26.	O1. Barry, A. Tanaka, Kentaro Nagamatsu, S. Bae, K. Lekhal, J. Matsushita, M. Deki, S. Nitta, Y. Honda and H. Amano : Effect of V/III ratio on the surface morphology and electrical properties of m-plane (1010) GaN homoepitaxial layers, Journal of Crystal Growth, Vol.468, 552-556, 2017. (Summary) We have investigated the effect of V/III ratio on the surface morphology, impurity concentration and electrical properties of mplane Gallium Nitride (GaN) homoepitaxial layers. Four-sided pyramidal hillocks are observed on the nominally on-axis mplane GaN films. Hillocks sizes relatively increase by increasing the V/III ratio. All facets of pyramidal hillocks exhibit well-defined step-terrace features. Secondary ion mass spectrometry depth profiles reveal that carbon impurities decrease by increasing the V/III ratio while the lowest oxygen content is found at an optimized V/III ratio of 900. Vertical Schottky barrier diodes fabricated on the mGaN samples were characterized. Low leakage current densities of the order of 1010 A/cm2 at 5 V are obtained at the optimum V/III ratio. Oxygen impurities and screw-component dislocations around hillocks are found to have more detrimental impact on the leakage current mechanism. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2016.12.012 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2016.12.012 (DOI: 10.1016/j.jcrysgro.2016.12.012)
27.	Noriko Usami, R. Miyagoshi, A. Tanaka, Kentaro Nagamatsu, M. Kushimoto, M. Deki, S. Nitta, Y. Honda and H. Amano: : Effect of dislocations on the growth of p-type GaN and on the characteristics of p-n diodes, Physica Status Solidi (A) Applications and Materials Science, Vol.214, No.8, 1600837, 2017. (Summary) We investigate the influence of crystal defects on ptype GaN grown by metalorganic vapor phase epitaxy. Sets of ptype GaN films were grown on sapphire substrates and on freestanding GaN (FGaN) substrates simultaneously using various EtCp2Mg flow rates. Although there is a difference of two orders of magnitude between the threading dislocation densities of ptype GaN grown on sapphire and FGaN substrates, there is no significant difference in hole concentration. However, there are problems with the surface morphology of ptype GaN grown on sapphire. The deterioration of the surface was caused by the difference in nanopipe density. The electrical properties of a pn junction diode formed on sapphire with a high density of nanopipes were observed using emission microscopy under both forward and reversebias conditions. Our results demonstrate that the nanopipes are electrically inactive, and that other types of threading dislocation have more influence on the currentvoltage characteristics. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.201600837 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.201600837 (DOI: 10.1002/pssa.201600837)
28.	Yasunori Kozuki, Kentaro Nagamatsu, M. Olsson, P. Song, M. Deki, S. Nitta, Y. Honda and H. Amano : Preflow trimethylaluminum treatment effect on GaN growth on SiC with an ultrathin interlayer, Japanese Journal of Applied Physics, Vol.55, No.5S, 05FB06, 2016. (Summary) Previously, we reported a growth method for GaN on SiC by metalorganic vapor phase epitaxy. By using a preflow trimethylaluminum treatment, the poor wetting problem of gallium on the SiC surface was alleviated, resulting in a 1.2-µm-thick crack-free GaN grown on an on-axis 6H-SiC(0001) substrate via an ultrathin AlGaN interlayer. In this study, the impact of the preflow trimethylaluminum treatment time is investigated to understand why a crack-free epilayer was realized. To demonstrate the electrical performance of devices formed by our technique, GaN/SiC vertical Schottky barrier diodes were fabricated and compared with GaN/AlN/SiC and GaN/GaN vertical Schottky barrier diodes. Compared with diodes including a high-resistance AlN interlayer, the series resistance of GaN/SiC Schottky barrier diodes incorporating the ultrathin interlayer with 5 s of TMAl treatment showed a marked reduction from 4.0 × 107 to 2.0 × 101 Ωcenterdotcm2. The ultrathin interlayer growth technique is expected to be applied in future GaN/SiC hybrid high-power and high-frequency devices. (Link to Publication Site) ● Publication site (DOI): 10.7567/JJAP.55.05FB06 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.7567/JJAP.55.05FB06 (DOI: 10.7567/JJAP.55.05FB06)
29.	T. Yamamoto, A. Tamura, Noriko Usami, T. Mitsunari, Kentaro Nagamatsu, S. Nitta, Y. Honda and H. Amano : Evaluation of excess in during metal organic vapor-phase epitaxy growth of InGaN by monitoring via in situ laser scattering, Japanese Journal of Applied Physics, Vol.55, No.5S, 05FD03, 2016. (Summary) Using an in situ laser absorption and scattering method, the surface roughness and incorporation of In in InGaN layers grown by metal organic vapor-phase epitaxy (MOVPE) were monitored. We observed that the laser light with energy higher than the GaN bandgap was fully absorbed in a GaN layer with a smooth film surface. On the other hand, we observed that the scattering laser light from the surface when the roughness of the InGaN surface increased owing to the formation of In droplets. Laser light with energy lower than the GaN bandgap was weakly absorbed by the GaN layer and was scattered at the back surface of the wafer. Furthermore, laser light intensity decreased during InGaN growth because of In incorporation. The threshold of trimethyl-In (TMIn) for the formation of In droplets as a function of growth temperature was determined using our in situ system. Moreover, we observed that the In droplets were removed by thermal or H2 treatment. The results indicate that multiwavelength laser absorption and scattering enable the optimization of the growth conditions for In-rich InGaN. (Link to Publication Site) ● Publication site (DOI): 10.7567/JJAP.55.05FD03 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.7567/JJAP.55.05FD03 (DOI: 10.7567/JJAP.55.05FD03)
30.	Yasunori Kozuki, A. Ohta, S. Miyazaki, Kentaro Nagamatsu, H. Lee, M. Olsson, Z. Ye, M. Deki, Y. Honda and H. Amano : The interface analysis of GaN grown on 0° off 6H-SiC with an ultra-thin buffer layer, Japanese Journal of Applied Physics, Vol.55, No.1, 10303, 2015. (Summary) Previously, we reported a growth method by metalorganic vapor phase epitaxy using a single two-dimensional growth step, resulting in 1.2-µm crack-free GaN directly grown on 6H-SiC substrate. The introduction of Al-treatment prior to the standard GaN growth step resulted in improved surface wetting of gallium on the SiC substrate. Transmission electron microscope and energy dispersive spectrometer analysis of the epitaxial interface to the SiC determined that an ultra-thin AlGaN interlayer had formed measuring around 23 nm. We expect our growth technique can be applied to the fabrication of GaN/SiC high frequency and high power devices. (Link to Publication Site) ● Publication site (DOI): 10.7567/JJAP.55.010303 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.7567/JJAP.55.010303 (DOI: 10.7567/JJAP.55.010303)
31.	Takahiro Kasai, Keiichiro Nonaka, K. Ban, K. Nagata, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Growth of low-dislocation-density AlGaN using Mg-doped AlN underlying layer, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.7, No.7-8, 2101--2103, 2010. (Summary) We report on a new technology for growing lowdislocationdensity AlGaN in which a Mgdoped AlN underlying layer is used. By growing AlxGa1xN on AlN:Mg with AlN molar fractions x of 0.3, 0.5 and 0.7, the density of misfit dislocations is much reduced compared with that in the case of growing AlGaN on undoped AlN. In addition, the surface becomes atomically flat. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200983591 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200983591 (DOI: 10.1002/pssc.200983591)
32.	Kentaro Nagamatsu, Daisuke Iida, Kenichiro Takeda, Kensuke Nagata, Takahiro Kasai, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki : Atomic layer epitaxy of AlGaN, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.7, No.10, 2368-2370, 2010. (Summary) Atomic layer epitaxy of AlGaN with an average growth rate of as high as 4.5 mm/h has been achieved by the highspeed switchingvalves (HSSVs) technique in a raisedpressure metalorganic vapor phase epitaxy system. Regarding the duration of group III metalorganics and NH3 gases input, 0.1 second for each injection time is found to be sufficient to realize AlGaN growth of one monolayer per cycle over a 2inch wafer with hydrogen and nitrogen carrier gases at a raised pressure. Lowtemperature growth of highquality AlGaN has been achieved using HSSVs. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200983862 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200983862 (DOI: 10.1002/pssc.200983862)
33.	Keiichiro Nonaka, Takahiro Kasai, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Defects in highly Mg-doped AlN, Physica Status Solidi (A) Applications and Materials Science, Vol.207, No.6, 1299-1301, 2010. (Summary) Microstructural analysis was conducted to observe Mgrelated defects in highly Mgdoped AlN on an undoped AlN layer grown by metalorganic vapor phase epitaxy. Pyramidal defects at a density of 1015cm3 were observed in the Mgdoped AlN layer with a Mg concentration of 2.5×1019cm3. The size and density of the pyramidal defects decreased at a low Mgdoped AlN layer with a Mg concentration. When the Mg concentration is high, defects of different shapes were formed in the Mgdoped AlN layer. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.200983504 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.200983504 (DOI: 10.1002/pssa.200983504)
34.	K. Nagata, T. Ichikawa, K. Takeda, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High-output-power AlGaN/GaN ultraviolet-light-emitting diodes by activation of Mg-doped p-type AlGaN in oxygen ambient, Physica Status Solidi (A) Applications and Materials Science, Vol.207, No.6, 1393-1396, 2010. (Summary) We demonstrated activation annealing of Mgdoped ptype Al0.17Ga0.83N in different gases. The hole concentration of Al0.17Ga0.83N annealed in oxygen is higher than that annealed in nitrogen or air. A hole concentration of 1.3×1016cm3 at room temperature was achieved by annealing in oxygen flow at 900°C. Secondary ion mass spectroscopy shows that hydrogen dissociation from Mgdoped Al0.17Ga0.83N is found to be enhanced by annealing in a flow of oxygen, compared with annealing in a flow of nitrogen. We confirmed the effect of activation annealing in oxygen flow on the performance of UV lightemitting diode (LED). At a DC current of 100mA, the output power of the LED annealed in oxygen flow at 900°C is four times higher than that of the LED annealed in nitrogen flow at 800°C. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.200983448 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.200983448 (DOI: 10.1002/pssa.200983448)
35.	T. Mori, Kentaro Nagamatsu, Keiichiro Nonaka, K. Takeda, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Crystal growth and p-type conductivity control of AlGaN for high-efficiency nitride-based UV emitters, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.6, No.12, 2621-2625, 2009. (Summary) Microstructural analysis was carried out to clarify the compositional dependence of the generation of dislocations in AlxGa1xN on an underlying AlN layer grown by metalorganic vapor phase epitaxy. When the film thickness is less than 1.5 μm, the threading dislocation density (TDD) increases with decreasing AlN molar fraction. However, when the film thickness exceeds 1.5 μm, TDD becomes maximum at x around 0.5. The growth of AlGaN on a grooved AlN template is effective in reducing TDD for all AlN molar fractions. TDD in AlGaN, which is close to binaries such as GaN and AlN, is a few 107 cm2, while for the intermediate composition with x around 0.5, TDD is still at mid 108 cm2. The activation energy of Mg in AlGaN is found to show a strong Mg concentration dependence with a negative onethird power law in Al0.25Ga0.75N and Al0.5Ga0.5N as well as in GaN. Overdoping of Mg causes an increase in the activation energy for every composition; from this, the optimum Mg concentration for realizing the highest hole concentration can be deduced. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200982547 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200982547 (DOI: 10.1002/pssc.200982547)
36.	K. Nagata, K. Takeda, T. Ichikawa, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Activation of Mg-Doped p-type Al_0.17Ga_0.83N in Oxygen Ambient, Japanese Journal of Applied Physics, Vol.48, No.10R, 101002, 2009. (Summary) Annealing in oxygen ambient was found to be effective for realizing a high hole concentration in p-type Al0.17Ga0.83N:Mg. The maximum hole concentration obtained was 1.3×1016 cm-3 at room temperature. Hydrogen dissociation from Mg-doped Al0.17Ga0.83N is found to be enhanced by annealing in a flow of O2 compared with annealing in a flow of N2. (Link to Publication Site) ● Publication site (DOI): 10.1143/JJAP.48.101002 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1143/JJAP.48.101002 (DOI: 10.1143/JJAP.48.101002)
37.	Kentaro Nagamatsu, K. Takeda, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Activation energy of Mg in Al_0.25Ga_0.75N and Al_0.5Ga_0.5N, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.6, No.S2-2, S437-S439, 2009. (Summary) The Mg concentration dependence of the acceptor activation energy in Al0.25Ga0.75N and Al0.5Ga0.5N was investigated. Temperaturedependent Hall effect measurements show that effective acceptor activation energy changes with a negative 1/3 power of Mg concentration, which means that the activation ratio increases with increasing Mg concentration. Similar to the case of GaN, however, overdoping of Mg causes serious compensation and a steep decrease of the hole concentration. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200880810 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200880810 (DOI: 10.1002/pssc.200880810)
38.	M. Suzuki, S. Sawai, K. Fukui, Kentaro Nagamatsu and H. Amano : Photoluminescence and excitation spectrum of Mg-doped p-type Al_xGa_1-xN, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.6, No.S2, S759-S762, 2009. (Summary) We have been measured the near band edge photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Mg doped AlGaN. PL and PLE peak energies were almost corresponding to those of undoped AlGaN. From the temperature dependent measurement of the PL spectra, the PL peak energy shift as a function of temperature showed S shaped behaviour. These results suggest that the mechanisms of the near band edge PL of AlGaN:Mg are basically similar to those of undoped AlGaN. Using the known spectral feature of undoped AlGaN which consists of main and LO phonon replica emission bands at even interval energy and same line width, the spectral decomposition of the PL spectrum reveals an additional band which is expected as the transition to the acceptor level arising from Mg doping. The temperature dependences of its peak energy and intensity suggest relative temperature shift of the acceptor level and also may imply the existence of another relaxation pathway. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200880905 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200880905 (DOI: 10.1002/pssc.200880905)
39.	Takahiro Kasai, K. Nagata, T. Mori, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Relaxation and recovery processes of AlxGa1-xN grown on AlN underlying layer, Journal of Crystal Growth, Vol.311, No.10, 2850-2852, 2009. (Summary) The processes as in title of relaxation of the lattice mismatch and the recovery of crystalline quality in thick AlxGa1xN on high-temperature-grown AlN were investigated. When x=0.3, rapid lattice relaxation occurred over a few microns, then the crystalline quality gradually recovered over 10 μm. In contrast, when x=0.7, relaxation of the lattice mismatch gradually occurred over 5 μm. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2009.01.028 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2009.01.028 (DOI: 10.1016/j.jcrysgro.2009.01.028)
40.	Kentaro Nagamatsu, Narihito Okada, Naofumi Kato, Takafumi Sumii, Akira Bandoh, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki : Effect of c-plane sapphire misorientation on the growth of AIN by high-temperature MOVPE, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.5, No.9, 3048-3050, 2008. (Summary) AlN layers were directly grown on sapphire substrates with slightly different miscut angles from the cplane by metalorganic vapor phase epitaxy at 1300 °C. By Xray diffraction analysis, the structural quality was found to improve with the increase in substrate offangle. When the substrate offangle was 0.5°, the Xray rocking curve (XRC) full widths at half maximum (FWHMs) of symmetric and asymmetric planes were 170 and 550 arcsec, respectively. At smaller offangle, XRCFWHMs were wider. When the substrate offangle was zero, the XRCFWHM was considerably inferior to that on 0.5ooffangle sapphire. The surface morphology was investigated. Atomic steps were observed on the substrates with a small misorientation. In contrast, macro steps appeared on largeroffangle sapphire substrates. (© 2008 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim) (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200779226 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200779226 (DOI: 10.1002/pssc.200779226)
41.	Kentaro Nagamatsu, N. Okada, Kunihiko Sugimura, Shyouzo Tsuzuki, F. Mori, K. Iida, A. Bando, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High-efficiency AlGaN-based UV light-emitting diode on laterally overgrown AlN, Journal of Crystal Growth, Vol.310, No.7-9, 2326-2329, 2008. (Summary) Ultraviolet light-emitting diodes (UV-LEDs) with a peak wavelength of 335 nm were fabricated on AlN/sapphire templates. As templates for the fabrication of UV-LEDs, planar AlN and epitaxial laterally overgrown (ELO) AlN on sapphire (0 0 0 1) substrates were compared. The output power of UV-LEDs grown on ELO-AlN was 27 times higher than that of UV-LEDs on the planar AlN template. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.jcrysgro.2007.11.152 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/j.jcrysgro.2007.11.152 (DOI: 10.1016/j.jcrysgro.2007.11.152)
42.	K. Iida, H. Watanabe, K. Takeda, T. Nagai, T. Sumii, Kentaro Nagamatsu, T. Kawashima, K. Balkrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki and A. Bandoh : High-efficiency AlGaN based UV emitters grown on high-crystalline-quality AlGaN using grooved AlN layer on sapphire substrate, Physica Status Solidi (A) Applications and Materials Science, Vol.204, No.6, 2000-2004, 2007. (Summary) Crackfree and lowdislocationdensity AlGaN was successfully grown on grooved AlN layer. UV lightemitting diodes (LEDs) with a peak wavelength of 330 nm on these AlGaN films were fabricated. The efficiency of the UV LEDs is found to be strongly affected by the crystalline quality of the underlying AlN. (© 2007 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim) (Link to Publication Site) ● Publication site (DOI): 10.1002/pssa.200674809 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssa.200674809 (DOI: 10.1002/pssa.200674809)
43.	H. Kasugai, Kentaro Nagamatsu, Y. Miyake, A. Honshio, T. Kawashima, K. Iida, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, H. Kinoshita and H. Shiomi : Light extraction process in moth-eye structure, Physica Status Solidi (C) Current Topics in Solid State Physics, Vol.3, No.6, 2165-2168, 2006. (Summary) We theoretically calculated the light extraction efficiency of the lightemitting diodes (LEDs) with a motheye structure by rigorous coupled wave analysis (RCWA). The dependences of light extraction efficiency on aspect ratio and period were measured. Light extraction efficiency was almost constant until the period of 170 nm and then gradually decreased with increasing of period. (© 2006 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim) (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200565319 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200565319 (DOI: 10.1002/pssc.200565319)
44.	Norio Tsuyukuchi, Kentaro Nagamatsu, Yoshinobu Hirose, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki : Low-Leakage-Current Enhancement-Mode AlGaN/GaN Heterostructure Field-Effect Transistor Using p-Type Gate Contact, Japanese Journal of Applied Physics, Vol.45 Part 2, No.8-11, L319, 2006. (Link to Publication Site) ● Publication site (DOI): 10.1143/JJAP.45.L319 (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-33646005526 (DOI: 10.1143/JJAP.45.L319, Elsevier: Scopus)

Academic Paper (Unrefereed Paper):

1.	Suzuki Akihiro, Kunihiro Otsuka, Hiroki Takanari, Kentaro Nagamatsu and Akihiro Shirai : 次世代光による細胞光応答の解明, LED総合フォーラム 2020 in 徳島論文集, Vol.P-17, 105-106, 2020.

Review, Commentary:

1.	Takeo Minamikawa, Takaaki Koma, Suzuki Akihiro, Kentaro Nagamatsu, Takeshi Yasui, Koji Yasutomo and Masako Nomaguchi : Inactivation of SARS-CoV-2 by deep ultraviolet light emitting diode: A review, Japanese Journal of Applied Physics, Vol.60, No.9, 090501, Aug. 2021. (Link to Publication Site) ● Publication site (DOI): 10.35848/1347-4065/ac19d1 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.35848/1347-4065/ac19d1 (DOI: 10.35848/1347-4065/ac19d1)
2.	Takeo Minamikawa, Takaaki Koma, 鈴木昭浩, Kentaro Nagamatsu, Takeshi Yasui, Koji Yasutomo and Masako Nomaguchi : Withコロナ時代に向けた深紫外LEDの活用法, クリーンテクノロジー, Vol.31, No.6, 1-5, Jun. 2021. (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1520857063623582336 (CiNii: 1520857063623582336)
3.	Takeo Minamikawa, Takaaki Koma, 鈴木昭浩, Kentaro Nagamatsu, Takeshi Yasui, Koji Yasutomo and Masako Nomaguchi : 深紫外LEDによる新型コロナウイルス不活化への試み, OPTRONICS, Vol.40, No.6, 132-137, May 2021.
4.	Takeo Minamikawa, Takaaki Koma, 鈴木昭浩, Kentaro Nagamatsu, Takeshi Yasui, Koji Yasutomo and Masako Nomaguchi : 深紫外LEDを用いた新型コロナウイルスの不活化, O plus E, Vol.43, No.2, 137-142, Mar. 2021. (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1521699231001747584 (CiNii: 1521699231001747584)
5.	Kentaro Nagamatsu and Takeshi Yasui : 期待される殺菌用・深紫外LED, 特別WEBコラム新型コロナウィルス禍に学ぶ応用物理, Oct. 2020.
6.	Kentaro Nagamatsu and 平山秀樹 : 深紫外LEDの需要と要素技術, OPTRONICS, Vol.9, No.465, 88-91, Sep. 2020. (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1522262180861343616 (CiNii: 1522262180861343616)

Proceeding of International Conference:

1.	Naoya Suto, Hiroto Seki, Takuya Kawakami, Keisuke Takabayashi, Eibon Tsuchiya, Tsubasa Endo, Yuusuke Takashima, Kentaro Nagamatsu, Yoshiki Naoi, Makoto Yamaguchi, Yohei Kobayashi and Takuro Tomita : Ohmic Contact Formation on 4H-SiC Using Pico-second Laser Irradiation, CLEO Pacific Rim 2024, Tu2I-3, Incheon, Aug. 2024.
2.	Kaito Fukuda, Naoya Suto, Hiroto Seki, Takuya Kawakami, Tsubasa Endo, Keisuke Takabayashi, Yohei Kobayashi, Makoto Yamaguchi, Kentaro Nagamatsu, Yuusuke Takashima, Yoshiki Naoi and Takuro Tomita : Effect of Picosecond Laser Irradiation on Metal Electrode of P-type Gallium Nitride, CLEO Pacific Rim 2024, Tu2I-2, Incheon, Aug. 2024.
3.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : A polarization-tunable coloration with wide dynamic range using highly lossy material-based metal/dielectric/metal- subwavelength grating, The 14th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META 2024), Vol.1A9, Toyama, Jul. 2024. (Keyword) nanophotonics
4.	Kouki Fujii, Atsushi Tomita, Yuuto Matsubara, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : Investigation of Ga Localization in AlGaN Growth with Step-Bunching at ultra-high temperature MOVPE growth, The 14th International Conference on Nitride Semiconductors (ICNS-14), Vol.MoP-GR-LN1, Fukuoka, Nov. 2023.
5.	Atsushi Tomita, Kouki Fujii, Takuya Kawakami, Hideki Hirayama, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : AlGaN and AlGaN/AlN superlattice growth by using ultra high-temperature MOVPE, The 14th International Conference on Nitride Semiconductors (ICNS-14), Vol.MoP-GR-13, Fukuoka, Nov. 2023.
6.	Atsushi Tomita, Kouki Fujii, Takuya Kawakami, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : GaN localization in high-temperature AlGaN growth over 1500, The 14th International Conference on Nitride Semiconductors (ICNS-14), Vol.MoP-GR-7, Fukuoka, Nov. 2023.
7.	Yuusuke Takashima, Shunsuke Furuta, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Deep ultraviolet to visible absorbing and sensing applications by stacking film with highly lossy ultrathin film, The 13th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META 2023), Vol.2A29, Paris, Jul. 2023. (Keyword) Perfect light absorber
8.	Kentaro Nagamatsu : High-temperature growth in AlN by MOVPE, ISPlasma2023, Gifu, Mar. 2023.
9.	Atsushi Tomita, Shota Tsuda, Takumi Miyagawa, Hirayama Hideki, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : The dependence of the V/III ratio in high-temperature AlN growth with several misorientations off-angle sapphire substrate, International Workshop on Nitride semiconductor 2022, Berlin, Oct. 2022.
10.	Takumi Miyagawa, Atsushi Tomita, Hideki Hirayama, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : Lateral epitaxial overgrowth by mass transport in AlN with the temperature of 1700, International Workshop on Nitride semiconductor 2022, Berlin, Oct. 2022.
11.	Takumi Miyagawa, Atsushi Tomita, Shota Tsuda, Hideki Hirayama, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : Dependence of c-plane sapphire misorientation angle in high temperature AlN growth and specific step bunching at large angle, International Workshop on Nitride semiconductor 2022, Berlin, Oct. 2022.
12.	Kentaro Nagamatsu, Takumi Miyagawa, Atsushi Tomita, Hideki Hirayama, Yuusuke Takashima and Yoshiki Naoi : The high-temperature growth in AlN with the unaffected parasitic reaction by Jet gas stream MOVPE, International Workshop on Nitride semiconductor 2022, Berlin, Oct. 2022.
13.	Kentaro Nagamatsu : Virus inactivation using ultraviolet LEDs, CLEO-PR 2022, Sapporo, Aug. 2022. (Link to Publication Site) ● Publication site (DOI): 10.1364/CLEOPR.2022.CTuW1_03 (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-85166468075 (DOI: 10.1364/CLEOPR.2022.CTuW1_03, Elsevier: Scopus)
14.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Ultraviolet violet applications utilizing high refractive index subwavelength structure with ultra-thin thickness, The 12th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META 2022), 1A8, Online, Jul. 2022. (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-85179872510 (Elsevier: Scopus)
15.	Shota Tsuda, Takumi Miyagawa, Reiya Aono, Atsushi Tomita, Hideki Hirayama, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : The improvement of crystal orientation in AlN with controlled inversion domain, Photonics West 2022, 12001-67, San Francisco, Jan. 2022.
16.	Shota Tsuda, Takumi Miyagawa, Reiya Aono, Atsushi Tomita, Hideki Hirayama, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : Threshold temperature in annihilation radius of dislocation for AlN, Photonics West 2022, 12001-66, San Francisco, Jan. 2022.
17.	Kentaro Nagamatsu, Shota Tsuda, Takumi Miyagawa, Reiya Aono, Hideki Hirayama, Yuusuke Takashima and Yoshiki Naoi : The reduction of adduct formation during high-temperature growth in AlN by jet gas stream metalorganic vapor phase epitaxy, Photonics West 2022, 12001-6, San Francisco, Jan. 2022.
18.	Yuusuke Takashima, Sasada Atsuki, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Design of AlN-subwavelength grating for deep ultraviolet wavelength reflector operating at 244 nm of wavelength, The 8th Optical Manipulation and Structured Materials Conference, OMC-P-02, Online, Apr. 2021. (Link to Publication Site) ● Publication site (DOI): 10.1117/12.2616175 (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-85120469004 (DOI: 10.1117/12.2616175, Elsevier: Scopus)
19.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : High refractive index contrast meta-structures for GaN-based and sensing applications operating at deep ultraviolet to visible wavelength, 13th International Symposium on Advanced Plasma Science and its Applications for Nitrides and Nanomaterials, 08pD07O, Online, Mar. 2021.
20.	Eiji Hase, Takeshi Yasui, Hirayama Hideki and Kentaro Nagamatsu : The improving resolution for dislocation analysis in GaN by three-photon microscopy, Photonics West 2020: OPTO2020, San Francisco, Feb. 2020.
21.	L. Yates, S. Usami, Kentaro Nagamatsu, G. Pavlidis, Y. Honda, H. Amano and S. Graham : Electrical and Thermal Analysis of Vertical GaN-on-GaN PN Diodes, International Workshop on Nitride Semiconductors (IWN2018), Kanazawa, Nov. 2018.
22.	Kentaro Nagamatsu, Uesugi K, K. Shojiki, H. Yoshida and H. Miyake : Improved emission intensity of UVC-LEDs using strain-relaxation layer, International Workshop on Nitride Semiconductors (IWN2018), Kanazawa, Nov. 2018.
23.	K. Uesugi, Y. Hayashi, K. Shojiki, Kentaro Nagamatsu, H. Yoshida and H. Miyake : Crystalline quality improvement and suppression of cracking for sputter-deposited high-temperature annealed AlN films by stress control, International Workshop on Nitride Semiconductors (IWN2018), Kanazawa, Nov. 2018.
24.	Kentaro Nagamatsu, Kenjiro Uesugi, Kanako Shojiki, Liu Xiaotong, Shiyu Xiao, Yusuke Hayashi, Harumasa Yoshida and Hideto Miyake : Effect of stress-relaxation layer in UVC-LEDs on sputter-deposited high-temperature annealedAlN/sapphire, 国際照明学会第十五届中国国际半导体照明论坛, 中国深セン, Oct. 2018.
25.	Y. Ando, Kentaro Nagamatsu, A. Tanaka, M. Deki, O.1. Barry, S. Usami, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Schottky Barrier Diodes Fabricated on Miscut m-planeSubstrates, International Symposium on Growth of -Nitrides (ISGN-7), Warsaw, Aug. 2018.
26.	M. Deki, K. Sone, K. Watanabe, F. Miura, Kentaro Nagamatsu, A. Tanaka, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Improvement of Electrical Stability of ALD-Al2O3/GaN Interfaceby UV/O3 Oxidation and Postdeposition Annealing, International Symposium on Growth of III-Nitrides (ISGN-7), Warsaw, Aug. 2018.
27.	A. Tanaka, Kentaro Nagamatsu, S. Usami, M. Kushimoto, M. Deki, S. Nitta, Y. Honda and H. Amano : Observation of Dislocation Propagation in GaN on GaN Structure With a Multiphoton Excitation Photoluminescence Microscope(invited), International Symposium on Growth of III-Nitrides (ISGN-7), Warsaw, Aug. 2018.
28.	M. Deki, Kentaro Nagamatsu, A. Tanaka, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Improvement of Electrical Stability in ALD-Al2O3/GaN Interface using UV/Ozone Oxidation and Post Deposition Annealing, International Symposium on Growth of III-Nitrides (ISGN-7), Warsaw, Aug. 2018.
29.	K. Uesugi, Y. Hayashi, K. Shojiki, S. Xiao, Kentaro Nagamatsu, H. Yoshida and H. Miyake : Crystal quality improvement of sputter-deposited AlN films on SiC substrates by high temperature annealing, International Symposium on Growth of III-Nitrides (ISGN-7), Warsaw, Aug. 2018.
30.	Z. Liu, S. Nitta, S. Usami, Kentaro Nagamatsu, Y. Robin, M. Kushimoto, M. Deki, Y. Honda and H. Amano : Effect of the environment temperature around the wafer on InGaN grown by metalorganic vapor phase epitaxy, 19th International Conference on Metalorganic Vapor Phase Epitaxy (ICMOVPE-XIX), Nara, Jun. 2018.
31.	Z. Ye, S. Nitta, Kentaro Nagamatsu, N. Fujimoto, M. Kushimoto, M. Deki, A. Tanaka, Y. Honda, M. Pristovsek and H. Amano : Ammonia Decomposition and Reaction by High-Resolution Mass Spectrometry forGroup III-Nitrides Epitaxial Growth, 19th International Conference on Metalorganic Vapor Phase Epitaxy (ICMOVPE-XIX), Nara, Jun. 2018.
32.	S. Nitta, Kentaro Nagamatsu, Z. Ye, H. Nagao, S. Miki, M. Kushimoto, M. Deki, A. Tanaka, Y. Honda, M. Pristovsek and H. Amano : Direct observation of ammonia decomposition and interaction with trimethylgallium in ametalorganic vapor phase epitaxy reactor, 19th International Conference on Metalorganic Vapor Phase Epitaxy (ICMOVPE-XIX), Nara, Jun. 2018.
33.	L. Yates, G. Pavlidis, S. Graham, S. Usami, Kentaro Nagamatsu, Y. Honda and H. Amano : Electrical and Thermal Analysis of Vertical GaN-on-GaN PN Diodes, 2018 17th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm), Vol.978-1-5386-1272-9, Mar. 2018. (Summary) In this study, we perform electrical and thermal characterization of vertical GaN pn diodes. One set of diode devices was subjected to passivation through the use of a polyimide film, while the other set of devices was non-passivated. Electroluminescence (EL) was performed on both sets of devices, and it was found that non-passivated devices demonstrated increased EL intensity at the mesa edges, most likely due to enhanced surface recombination, and subsequently showed I-V characteristics that outperformed the passivated devices in terms of power handling capabilities at high forward voltages. Thermoreflectance imaging was used to evaluate the temperature distribution of the metal contact for 130 μm diodes, and it was found that a very uniform distribution was consistent even for very large forward voltage bias. Additional thermal characterization was carried out using time-domain thermoreflectance (TDTR) and depth dependent measurements demonstrated an inhomogeneity in the thermal conductivity of the diodes when measuring from the heavily doped p-type region. (Link to Publication Site) ● Publication site (DOI): 10.1109/ITHERM.2018.8419481v (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1109/ITHERM.2018.8419481v (DOI: 10.1109/ITHERM.2018.8419481v)
34.	M. Ogura, Y. Ando, S. Usami, Kentaro Nagamatsu, Kushimoto M, M. Deki, A. Tanaka, S. Nitta, Y. Honda, Pristovsek M, H. Kawai, S. Yagi and H. Amano : Development of sustainable smart society based on transformative electronics, 2017 IEEE International Electron Devices Meeting, Vol.30, No.1, 1-4, Dec. 2017. (Summary) We will review three recent advances. Defects which cause leakage under a high-voltage reverse-biased condition were identified in GaN pin diodes grown on free-standing GaN substrates. The performances of GaN-based horizontal-heterostructure superjunction high-electron-mobility transistor and a GaN-nanorod-based vertical pn-superjunction diode were simulated. A vertical pn-superjunction was fabricated using GaN nanorod growth technology. (Link to Publication Site) ● Publication site (DOI): 10.1109/IEDM.2017.8268477 (Link to Search Site for Scientific Articles) ● Summary page in Scopus @ Elsevier: 2-s2.0-85045198777 (DOI: 10.1109/IEDM.2017.8268477, Elsevier: Scopus)
35.	S. Nitta, Z. Liu, S. Usami, Kentaro Nagamatsu, M. Kushimoto, M. Deki, A. Tanaka, Y. Honda, M. Pristovsek and H. Amano : In-situ and biased characterization of nitride semiconductor crystalfor the advanced optical and power electronic devices, 8th International Conference and Exhibition on Lasers, Optics & Photonics, Nov. 2017.
36.	X. Yang, S. Nitta, Kentaro Nagamatsu, M. Pristovsek, Y. Liu, Y. Honda and H. Amano : Growth and Structural Characterization of Hexagonal Boron Nitride on Sapphire, International Workshop on UV Materials and Devices 2017 (IWUMD 2017), Fukuoka, Nov. 2017.
37.	Y. Honda, A. Tanaka, S. Usami, Kentaro Nagamatsu, S. Nitta and H. Amano : Dislocation observation of GaN/GaN homo epitaxial growth film by Multi-photon absorption hotoluminescence, 6th International Workshop Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano 2017), Como, Sep. 2017.
38.	M. Deki, Y. Ando, Kentaro Nagamatsu, A. Tanaka, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Deep Levels in Homoepitaxialm-plane GaN Schottky Barrier Diodes, 10th International Workshop on Bulk Nitride Semiconductors IWBNS-X, Finland, Sep. 2017.
39.	X. Yang, S. Nitta, Kentaro Nagamatsu, Y. H. Liu, Y. Honda and H. Amano : Hexagonal boron nitride deposition and growth evolution by pulsed-mode MOVPE technique, International Conference on Nitride Semiconductors-12, Strasbourg, Jul. 2017.
40.	A. Tanaka, O. 1Barry, Kentaro Nagamatsu, M. Deki, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : m-plane GaN Schottky barrier diode fabricated with MOVPE layer on several off-angled GaN substrate, International Conference on Nitride Semiconductors-12, Strasbourg, Jul. 2017.
41.	M. Deki, K. Sone, J. Matsushita, Kentaro Nagamatsu, A. Tanaka, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Crystal Plane Dependence of Interface States Density in c- and m-plane GaN MOS Capacitors, International Conference on Nitride Semiconductors-12, Strasbourg, Jul. 2017.
42.	S. Usami, Y. Ando, A. Tanaka, Kentaro Nagamatsu, M. Kushimoto, M. Deki, S. Nitta, Y. Honda and H. Amano : Correlation between dislocations and leakage current of p-n diodes on free-standing GaN substrate, International Conference on Nitride Semiconductors-12 (ICNS12), Strasbourg, Jul. 2017.
43.	X. Yang, S. Nitta, Kentaro Nagamatsu, M. Pristovsek, Y. Liu, Y. Honda and H. Amano : Impact of temperature on pulsed-mode MOCVDHexagonal Boron Nitride on Sapphire, SPIE Photonic West, San Francisco, Jan. 2017.
44.	S. Usami, R. Miyagoshi, Kentaro Nagamatsu, A. Tanaka, S. Nitta, M. Deki, Y. Honda and H. Amano : Effect of dislocations on the growth of p-type GaN and device characteristics, International Workshop on Nitride Semiconductors 2016 (IWN2016), Orlando, Oct. 2016.
45.	Z. Sun, A. Ohta, S. Miyazaki, X. Yang, P. Song, Kentaro Nagamatsu, S. Nitta, Y. Honda and H. Amano : GaN Growth on m-plane SiC Substrate with an Ultrathin Interlayer, International Workshop on Nitride Semiconductors 2016 (IWN2016), Orlando, Oct. 2016.
46.	X. Yang, S. Nitta, Kentaro Nagamatsu, Y. H. Liu, Z. Sun, Z. Ye, J. Matsushita, Y. Honda and H. Amano : The Influence of Residual Boron in Reactor on the Quality of GaN Crystal Grown via MOVPE, International Workshop on Nitride Semiconductors 2016 (IWN2016), Orlando, Oct. 2016.
47.	S. Nitta, Kentaro Nagamatsu, R. Miyagoshi, Z. Ye, Y. Honda and H. Amano : In-LineNH3 Reactant Analysis on Nitride Semiconductor Metalorganic Vapor Phase Epitaxy via High-ResolutionMass Spectrometry, International Workshop on Nitride Semiconductors 2016 (IWN2016), Orlando, Oct. 2016.
48.	A. Tanaka, O. 1 Barry, Kentaro Nagamatsu, J. Matsushita, M. Deki, M. Kushimoto, S. Nitta, Y. Honda and H. Amano : Facet Distribution of Leakage Current and Carrier Concentration in m-plane GaN Schottky BarrierDiode Fabricated with MOVPE, International Workshop on Nitride Semiconductors 2016 (IWN2016), Orlando, Oct. 2016.
49.	T. Yamamoto, A. Tamura, Kentaro Nagamatsu, M. Deki, S. Nitta, Y. Honda and H. Amamo : InGaN surface roughness recovery by hydrogen treatment as monitored by in situ laser scattering, the 18th International Conference on Crystal Growth and Epitaxy (ICCGE-18), Nagoya, Aug. 2016.
50.	Z. Sun, Kentaro Nagamatsu, M. Deki, S. Nitta, Y. Honda and H. Amano : GaN Growth on a-plane SiC Substrate with an Ultrathin Interlayer, he 18th International Conference on Crystal Growth and Epitaxy (ICCGE-18), Nagoya, Aug. 2016.
51.	O. 1 Barry, A. Tanaka, Kentaro Nagamatsu, S.Y. Bae, K. Lekhal, M. Deki, S. Nitta, Y. Honda and H. Amano : Reduction of leakage current density in homoepitaxial m-plane GaN by controlling V/III ratios for high-power device applications, the 18th International Conference on Crystal Growth and Epitaxy (ICCGE-18), Nagoya, Aug. 2016.
52.	Y. Honda, T. Yamamoto, A. Tamura, S. Usami, Kentaro Nagamatsu, M. Kushimoto, S. Nitta and H. Amano : In-situ monitoring of Laser absorption and scattering method during InGaN growthby MOVPE, The 7th International Symposium on Advanced Science and Technology of Silicon Materials, Hawaii, 2016.
53.	T. Yamamoto, A. Tamura, S. Usami, Kentaro Nagamatsu, S. Nitta, Y. Honda and H. Amano : Growth of InGaN well layer with an in-situ monitoring system, 6th International Symposium on Growth of III-Nitrides (ISGN-6), Hamamatsu, Nov. 2015.
54.	Z. Ye, Z. Sun, Kentaro Nagamatsu, M. Deki, S. Nitta, Y. Honda and H. Amano : Reduction of Residual Carbon on Un-doped GaNGrown usingMetal Organic Hydrogen Chloride Vapor Phase Epitaxy, 6th International Symposium on Growth of III-Nitrides (ISGN-6), Hamamatsu, Nov. 2015.
55.	M. Kawaguchi, O. Imafuji, Kentaro Nagamatsu, K. Yamanaka and T. Katayama : Design and Lasing Characteristics of GaN Vertical Elongated Cavity Surface Emitting Lasers, SPIE Gallium Nitride Materials and Devices IX, Mar. 2014.
56.	M. Kawaguchi, O. Imafuji, Kentaro Nagamatsu, K. Yamanaka, S. Takigawa and T. Katayama : Design and lasing characteristics of GaN vertical elongated cavity surface emitting lasers, Proceedings of SPIE, Vol.8986, 8986K, Mar. 2014. (Summary) We report on design and lasing characteristics of GaN vertical-cavity surface-emitting lasers (VCSELs) with an elongated cavity for use in uniform elements of a two-dimensional (2D) laser array. Calculations of VCSELs with the elongated cavity taking into account the wavelength dispersion of the refractive index show that the transverse mode spacing can be significantly narrower than the gain spectrum with a small tradeoff of the differential quantum efficiency. The result clearly shows that the elongated cavity is robust against the thermally induced peakshift of the gain spectrum, and thus preferable for use in elements of density packed laser array for which uniform operation of each element is crucial. The VCSEL with the elongated cavity fabricated by the wafer thinning technique operates under current injection by using highly reflective distributed Bragg reflectors (DBRs) made of transparent ZrO2 and SiO2 film stacks. Together with high reflectivity and wide stop band of the DBR, the elongated cavity of 6 μm (36λ) allows multimode lasing oscillation with a mode spacing of 2.9 nm, which is one order of magnitude narrower than the gain spectrum. In addition, we demonstrate a 5x5 GaN VCSEL array. (Link to Publication Site) ● Publication site (DOI): 10.1117/12.2037484 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1117/12.2037484 (DOI: 10.1117/12.2037484)
57.	T. Onishi, O. Imafuji, Kentaro Nagamatsu, M. Kawaguchi, K. Yamanaka and S. Takigawa : Continuous Wave Operation of GaN Vertical Cavity Surface Emitting Lasers at Room Temperature, IEEE Journal of Quantum Electronics, Vol.48, No.9, 1107-1112, Jun. 2012. (Summary) We report on continuous wave lasing characteristics of GaN vertical cavity surface emitting lasers (VCSELs). The VCSEL operates at room temperature under current injection by using highly reflective distributed Bragg reflectors (DBRs) made up of transparent ${m ZrO}_{2}$ and ${m SiO}_{2}$ film stacks. Together with high reflectivity and the wide stop band of the DBR, the long cavity of 6 $u{m m}$ allows multimode lasing oscillation with narrow mode spacing of 2.9 nm. In addition, a short cavity structure of 2 $u{m m}$ is fabricated and shows quasi-single mode operation. The spacing of the lasing modes shows a clear dependence of the actual cavity lengths with fairly good agreement to theory taking account of the refractive index dispersion.
58.	K. Orita, Meneghini M, Ohno H, Trivellin N, N. Ikedo, S. Takigawa, Yuri M, T. Tanaka, E. Zanoni, G. Meneghesso, T. Onishi, O. Imafuji, Kentaro Nagamatsu, Tomoyuki Kawaguchi, K. Yamanaka, Kwon OK, Baek YS, YC. Chung, C. Wang, Grillot F and J. Even : Dye Lasers Lasing from Water Solution of Rhodamine 6G/Gold Nanoparticles: Impact of SiO2-Coating on Metal Surface. L. Dong, IEEE Journal of Quantum Electronics, Vol.48, No.9, 1105-1106, Mar. 2012.
59.	H. Amano, K. Nagata, D. Iida, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama and I. Akasaki : Atomic layer epitaxy of GaInN and AlGaN by high pressure MOVPE, APS March Meeting 2010, Portland, Mar. 2010.
60.	H. Amano, K. Nagata, Kentaro Nagamatsu, D. Iida, M. Iwaya, S. Kamiyama and I. Akasaki : Increased pressure digital metalorganic vapor phase epitaxy system with high-speed switching valves for growing high-In-content GaInN, Proceedings of SPIE, Vol.7617, Feb. 2010. (Link to Publication Site) ● Publication site (DOI): 10.1117/12.848616 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1117/12.848616 (DOI: 10.1117/12.848616)
61.	H. Amano, K. Nagata, D. Iida, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama and I. Akasaki : New MOVPE system for next generation AlGaInN growth, The 4th International Conference on LED and Solid-State Lighting (LED 2010), Korea, 2010.
62.	D. Iida, Kentaro Nagamatsu, K. Nagata, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Growth of GaInN Films by High Pressure MOVPE System at 200kPa, 8th International Conference on Nitride Semiconductors (ICNS-8), 韓国, Oct. 2009.
63.	K. Nonaka, T. Asai, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Defects in Highly Mg-Doped AlN, 8th International Conference on Nitride Semiconductors (ICNS-8), 韓国, Oct. 2009.
64.	T. Asai, K. Nonaka, K. Ban, K. Nagata, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Growth of Low-Dislocation-Density AlGaN using Mg-Doped AlN Underlying Layer, 8th International Conference on Nitride Semiconductors (ICNS-8), 韓国, Oct. 2009.
65.	Kentaro Nagamatsu, D. Iida, K. Takeda, K. Nagata, T. Asai, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High Pressure MOVPE System with High-Speed Switching Valves for the Realization of High-Quality AlGaN at Low Temperatures, International Conference on Nitride Semiconductors (ICNS-8), 韓国, Oct. 2009.
66.	K. Nagata, T. Ichikawa, K. Takeda, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High Output Power AlGaN/GaN Ultraviolet Light Emitting Diodes by Activation of Mg-Doped P-Type AlGaN in Oxygen Ambient, 8th International Conference on Nitride Semiconductors (ICNS-8), 韓国, Oct. 2009.
67.	Kentaro Nagamatsu, Daisuke Iida, Kenichiro Takeda, Kensuke Nagata, Takahiro Kasai, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki : Atomic layer epitaxy of AlGaN, The 36 th International Symposium on Compound Semiconductors, Sep. 2009. (Summary) Atomic layer epitaxy of AlGaN with an average growth rate of as high as 4.5 mm/h has been achieved by the highspeed switchingvalves (HSSVs) technique in a raisedpressure metalorganic vapor phase epitaxy system. Regarding the duration of group III metalorganics and NH3 gases input, 0.1 second for each injection time is found to be sufficient to realize AlGaN growth of one monolayer per cycle over a 2inch wafer with hydrogen and nitrogen carrier gases at a raised pressure. Lowtemperature growth of highquality AlGaN has been achieved using HSSVs. (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200983862 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200983862 (DOI: 10.1002/pssc.200983862)
68.	H. Amano, Kentaro Nagamatsu, K. Takeda, M. Iwaya, S. Kamiyama and I. Akasaki : Growth and conductivity control of high quality AlGaN and its application to high performance ultraviolet laser diodes, Semiconducting and Insulating Materials Conference (SIMC), リトアニア共和国, Jun. 2009.
69.	Kentaro Nagamatsu, K. Takeda, T Mori, H Tsuzuki, M Iwaya, S Kamiyama and I Akasaki : Growth and conductivity control of high quality AlGaN and its application to high-performance ultraviolet laser diodes, Proceedings of SPIE, Vol.7216, 72161B, Feb. 2009. (Link to Publication Site) ● Publication site (DOI): 10.1117/12.808381 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1117/12.808381 (DOI: 10.1117/12.808381)
70.	H. Amano, H. Tsuzuki, T. Mori, K. Takeda, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama and I. Akasaki : Challenge for short wavelength semiconductor UV laser diodes, SPIE Photonics West, San Jose, Jan. 2009.
71.	H. Amano, Kentaro Nagamatsu, K. Takeda, T. Mori, H. Tsuzuki, M. Iwaya, S. Kamiyama and I. Akasaki : Growth and conductivity control of high quality AlGaN and its application to high-performance ultraviolet laser diodes, Gallium Nitride Materials and Devices IV (SPIE OE106), San Jose, Jan. 2009. (Summary) A microstructure in AlGaN with a whole compositional range on an AlN/sapphire template is systematically investigated. At the interface between AlGaN and AlN, misfit dislocation density increases with Ga composition in AlGaN. However, most misfit dislocations bend owing to the compressive stress and form loops, by which threading dislocation density is markedly reduced if the thickness exceeds several microns. The effective acceptor energy of Mg in Al0.5Ga0.5N is found to depend on Mg concentration with a negative one-third power. A SiO2/AlN dielectric multilayer mirror is very effective for controlling the reflectivity of the Fabry-Perot resonator mirrors at the cleaved edge of the ultraviolet (UV) laser diodes (LDs). A UV LD with an emission wavelength of 358 nm shows a threshold current density as low as 3.9 KA/cm2 at room temperature.
72.	Kentaro Nagamatsu, K. Takeda, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Activation energy of Mg in AlGaN, International Warkshop on Nitride semiconductor 2008 (IWN2008), Montreux, Switzerland, Oct. 2008.
73.	T. Asai, K. Nagata, T. Mori, Kentaro Nagamatsu, N. Okada, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Relaxation process of AlxGa1-xN grown on high-crystalline-quality AlN, Second International Symposium on Growth of III-Nitrides (ISGN-2), Shizuoka, Jul. 2008.
74.	H. Amano, H. Tsuzuki, K. Takeda, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama and I. Akasak : Short wavelength semiconductor laser diodes, Japan- Brazil Memorial Symposium on Science and Technology for the Celebration of 100 Years of Japanese Immigration in Brazil, Brazil, Mar. 2008.
75.	H. Amano, N. Kato, N. Okada, T. Kawashima, K. Iida, Kentaro Nagamatsu, M. Imura, K. Balakrishnan, M. Iwaya, S. Kamiyama and I. Akasaki : Nitride-Based UV Lasers, The 20th Annual Meeting of the IEEE Lasers & Electro-Optics Society (LEOS 2007), Florida, Oct. 2007.
76.	H. Amano, Kentaro Nagamatsu, K. Iida, N. Okada, T. Kawashima, M. Iwaya, S. Kamiyama and I. Akasaki : AlGaN-based UV light emitting devices, LEOS Annual 2007; 20th Annual Meeting of the IEEE Lasers and Electro-Optics Society, Florida, Oct. 2007.
77.	Kentaro Nagamatsu, Narihito Okada, Naofumi Kato, Takafumi Sumii, Akira Bando, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano and Isamu Akasaki : Effect of cplane sapphire misorientation on the growth of AlN by hightemperature MOVPE, The 34th International Symposium on Compound Semiconductors, Oct. 2007. (Summary) AlN layers were directly grown on sapphire substrates with slightly different miscut angles from the cplane by metalorganic vapor phase epitaxy at 1300 °C. By Xray diffraction analysis, the structural quality was found to improve with the increase in substrate offangle. When the substrate offangle was 0.5°, the Xray rocking curve (XRC) full widths at half maximum (FWHMs) of symmetric and asymmetric planes were 170 and 550 arcsec, respectively. At smaller offangle, XRCFWHMs were wider. When the substrate offangle was zero, the XRCFWHM was considerably inferior to that on 0.5ooffangle sapphire. The surface morphology was investigated. Atomic steps were observed on the substrates with a small misorientation. In contrast, macro steps appeared on largeroffangle sapphire substrates. (© 2008 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim) (Link to Publication Site) ● Publication site (DOI): 10.1002/pssc.200779226 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/pssc.200779226 (DOI: 10.1002/pssc.200779226)
78.	K. Iida, F. Mori, H. Watanabe, K. Takeda, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, H. Maruyama, T. Takagi and A. Bandoh : UV Emitters Grown on High Crystalline Quality AlGaN on Sapphire, The 7th International Conference of Nitride Semiconductors, Las Vegas, Sep. 2007. (Summary) We fabricated UV-LED on 3 types of the underlying layers. All samples were grown on AlN on sapphire substrates by MOVPE. Type 1 is UV-LED on AlN template. Type 2 is ELO Al0.25Ga0.75N on grooved AlN. Type 3 is ELO Al0.25Ga0.75N on grooved Al0.25Ga0.75N on AlN template. We compared how these device performances influenced by the difference of the underlying layer. Light output intensity of UV-LED fabricated on ELO Al0.25Ga0.75N on grooved Al0.25Ga0.75N luminous intensity of this UV- LED is the stronger than that of other samples from the L-I curves. The improvement of this luminous intensity originates in a decrease in the defect in AlGaN and control of strain.
79.	N. Okada, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, H. Maruyama, T. Takagi, A. Bando, H. Murotani and Y. Yamada : Stimulated Emission from Nonpolar AlN, the 7th International Conference of Nitride Semiconductors (ICNS-7), Las Vegas, Sep. 2007. (Summary) Nonpolar AlN is attracted much attention to realize high-performance UV light emitting devices due to elimination of the internal electric field induced by piezoelectricity in the quantum well. However, experimental evaluation of the advantage of nonpolar plane had been still hindered because of the presence of high-density dislocations and stacking faults in nonpolar AlN layer. We have succeeded to achieve high-quality polar and nonpolar epitaxial lateral overgrown (ELO) AlN layers by high-temperature metal-organic vapor phase epitaxy (HT-MOVPE). In this letter, we report stimulated emission from nonpolar and polar AlN by optical excitation. Then, stimulated emission from nonpolar AlN was confirmed and a threshold excitation power density of nonpolar AlN is almost the same as that of polar AlN both at 8K and 100K.
80.	Kentaro Nagamatsu, N. Okada, T. Shyouzo, F. Mori, K. Sugumura, K. Iida, A. Bando, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Epitaxial lateral overgrowth of low dislocation density AlN by high temperature MOVPE and fabrication of UV optoelectronics devices, The 15th International Conference on Crystal Growth, Salt Lake City, Aug. 2007.
81.	K. Iida, H. Watanabe, K. Takeda, T. Nagai, T. Sumii, Kentaro Nagamatsu, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Comparison of the simulation and experiments of the nitride-based UV light emitting diodes, Proceedings of SPIE, Vol.6468, Feb. 2007. (Summary) In attempt to prepare a high performance AlxGa1-xN based UV-B LED, a computer simulation has been performed on a typical UV-LED structure to find out the effect of threading dislocations on non-radiative recombination process. UVB LED structures were formed on using GaN and AlN based layers for comparison. Cracks were generated in the device structure formed on GaN underlayer. No cracks were observed on the device structure formed on AlN under layer. Much better structure was formed when the base AlN was grown by high temperature MOVPE. (Link to Publication Site) ● Publication site (DOI): 10.1117/12.717174 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1117/12.717174 (DOI: 10.1117/12.717174)
82.	K. Iida, H. Watanabe, K. Takeda, T. Nagai, Kentaro Nagamatsu, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Comparison of the simulation and experiments of the nitride-based UV-light-emitting diodes, SPIE Photonic West, San Jose, Jan. 2007.
83.	H. Amano, H. Tsuzuki, T. Mori, K. Takeda, Kentaro Nagamatsu, M. Iwaya, S. Kamiyama and I. Akasaki : Growth of low-dislocation-density AlGaN for the realization of high-performance ultraviolet laser diodes, The 3rd International Conference on Display and Solid-State Lighting, 2007.
84.	H. Amano, N. Kato, N. Okada, T. Kawashima, K. Iida, Kentaro Nagamatsu, M. Imura, K. Balakrishnan, Iwaya M, Kamiyama S, I. Akasaki and A. Bandoh : Nitride-Based UV Lasers, LEOS 2007 - IEEE Lasers and Electro-Optics Society Annual Meeting Conference Proceedings, 380-381, 2007. (Summary) The ultraviolet (UV) laser diode (LD) is attracting much attention for various novel applications such as in medical engineering, sterilization and high density optical storage. Group III nitrides are one of the most promising candidates to realize UV LD. The external quantum efficiency of group-Ill nitride-based light-emitting diodes (LEDs) with emission wavelength shorter than 360 nm is still far inferior to that of nitride-based visible-short-wavelength LEDs. Simulation results show that there is no theoretical barrier which hiders the realization of short wavelength UV LDs (Chow, 2005). At the moment, however, the shortest emission wavelength of nitride-based LD is limited to 343nm on SiC (Edmond, 2004) and 350.9 nm on a sapphire substrate (Iida, 2004). In order to overcome the barrier for emission wavelength and to realize much shorter wavelength UV LDs, in addition to the control of conductivity for both n-type and p-type layers, the growth of low-dislocation-density high-Al-content AlGaN with low internal loss is essential.
85.	K. Balakrishnan, M. Imura, K. Iida, Kentaro Nagamatsu, H. Sugimura, T. Nagai, T. Sumii, S. Mori, A. Bandoh, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High temperature MOVPE growth of AlN and AlxGa1-xN, 4th International Workshop of Nitride Semiconductors, Kyoto, Oct. 2006.
86.	K. Balakrishnan, M. Imura, K. Iida, Kentaro Nagamatsu, S. Mori, A. Bandoh, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High temperature MOVPE growth of AlN and AlxGa1-xN, 4th International Workshop of Nitride Semiconductors, Kyoto, Oct. 2006.
87.	B. Krishnan, M. Imura, K. Iida, Kentaro Nagamatsu, Kunihiko Sugimura, T. Nagai, T. Sumii, F. Mori, A. Bandoh, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : High Temperature MOVPE Growth of AlxGa1-xN (0.2-1) Layers on Sapphire and SiC Substrates for the Fabrication Deep UV Optical Devices'' MRS OnlineProceedingsLibrary(OPL), Materials Research Society Symposia Proceedings, Vol.955, No.I04, 03, 2006. (Link to Publication Site) ● Publication site (DOI): 10.1557/PROC-0955-I04-03 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1557/PROC-0955-I04-03 (DOI: 10.1557/PROC-0955-I04-03)
88.	N. Tsuyukuchi, Kentaro Nagamatsu, Yoshinobu Hirose, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Normally Off-Mode AlGaN/GaN Heterostructure Field Effect Transistor Using P-Type Gate Contact, Materials Research Society Symposia Proceedings, Vol.892, 383, 2006.
89.	N. Tsuyukuchi, Kentaro Nagamatsu, H. Yoshinobu, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Normally Off-Mode AlGaN/GaN HFET with p-Type Gate Contact, Materials Research Society Fall Meeting, Vol.FF15.3, Boston, Nov. 2005.
90.	Y. Okadome, Y. Tsuchiya, H. Furukawa, Kentaro Nagamatsu, A. Honshio, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Realization of high-crystallinity a-plane GaN grown on r-plane sapphire substrate for high-performance light-emitting device, Materials Research Society Fall Meeting, Vol.FF7.7/EE5.7, Boston, Nov. 2005.
91.	N. Tsuyukuchi, Kentaro Nagamatsu, Y. Hirose, M. Iwaya, S. Kamiyama, H. Amano and I. Akasaki : Normally Off-Mode AlGaN/GaN HFET with p-Type Gate Contact, MRS Online Proceedings Library Archive, Vol.892, No.FF15, 03, 2005. (Summary) A normally off-mode AlGaN/GaN heterostructure field effect transistor (HFET) using a p-type GaN gate was fabricated and their static properties were compared with those of HFET having a Schottky gate. HFET having a p-GaN gate contact shows a very low leakage current density of 18.2 μA/mm at VGS and VDS of 0 V and 20 V, respectively. (Link to Publication Site) ● Publication site (DOI): 10.1557/PROC-0892-FF15-03P (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1557/PROC-0892-FF15-03P (DOI: 10.1557/PROC-0892-FF15-03P)

Proceeding of Domestic Conference:

1.	Yuusuke Takashima, Kentaro Nagamatsu and Yoshiki Naoi : Ultra-wide dynamic structural colors with width-modulated Cr-subwavelength grating on Ni/SiO2 films, 第85回応用物理学会秋季学術講演会JSAP-Optica Joint Symposia 2024, Vol.16p-B4-3, (Keyword) nanophotonics
2.	FUKUDA Kaito, SUTO Naoya, SEKI Hiroto, KAWAKAMI Takuya, 遠藤翼, 高林圭佑, 小林洋平, 山口誠, Kentaro Nagamatsu, Yuusuke Takashima, Yoshiki Naoi and Takuro Tomita : p型窒化ガリウム上Ni/Au電極へのサブピコ秒レーザー照射による電気特性改質, 第85回応用物理学会秋季学術講演会, 18p-A25-13, Sep. 2024.
3.	SUTO Naoya, 関宏都, 川上拓哉, 高林圭佑, 土屋叡本, 遠藤翼, Yuusuke Takashima, Kentaro Nagamatsu, Yoshiki Naoi, 山口誠, Tatsuya Okada, 小林洋平 and Takuro Tomita : 超短パルスレーザーによるSiC上オーミック電極の電気特性のパルス時間幅依存性, 第85回応用物理学会秋季学術講演会, 18p-A25-11, Sep. 2024.
4.	FUKUDA Kaito, SUTO Naoya, SEKI Hiroto, KAWAKAMI Takuya, 遠藤翼, 高林圭佑, 小林洋平, 山口誠, Kentaro Nagamatsu, Yuusuke Takashima, Yoshiki Naoi and Takuro Tomita : p-GaN/電極界面へのピコ秒レーザー照射による影響評価, 2024年度応用物理・物理系学会中国四国支部合同学術講演会, Bp-5, Jul. 2024.
5.	TAKAYANAGI Yusuke, FUJII Koki, MATSUBARA Yuto, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : N極性核形成層を用いたAlNの低転位化手法, 中四国応用物理学会, Jul. 2024.
6.	FUJII Koki, MATSUBARA Yuto, TAKAYANAGI Yusuke, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 次世代高移動度HEMTチャネル層に向けたAlNステップ形状改善に関する研究, 中四国応用物理学会, Jul. 2024.
7.	MATSUBARA Yuto, FUJII Koki, TAKAYANAGI Yusuke, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 有機金属気相成長法による超高温AlGaN成長, 中四国応用物理学会, Jul. 2024.
8.	NAGAO Yuto, Yoshiki Naoi, Masanobu Haraguchi, Kentaro Nagamatsu and Yuusuke Takashima : Geサブ波長格子内の振幅変調波を利用した GaN系紫外LEDの偏光制御, 2024年度応用物理・物理系学会中国四国支部合同学術講演会, Jul. 2024.
9.	MATSUBARA Yuto, TOMITA Atsushi, FUJII Koki, TAKAYANAGI Yusuke, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 高温 AlGaN 成長における供給 Al/Ga モル比と AlN モル分率の関係, 第71回応用物理学会春季学術講演会, 24a-21C-2, Mar. 2024.
10.	TAKAYANAGI Yusuke, TOMITA Atsushi, FUJII Koki, MATSUBARA Yuto, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : TMAパルス供給によるAlNの高温成長, 第71回応用物理学会春季学術講演会, 24a-21C-3, Mar. 2024.
11.	Yua Okano, Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : 高屈折率基板上AlNサブ波長回折格子を用いた深紫外域における共鳴反射の狭帯域化, 第71回応用物理学会春季学術講演会, 24a-P06-3, Mar. 2024. (Keyword) nanophotonics
12.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Refractive index detection using highly lossy Ni/SiO2/Cr-subwavelength grating structure, 第71回応用物理学会春季学術講演会, 24a-P06-2, Mar. 2024. (Keyword) nanophotonics / electrical and electronic materials
13.	FUKUDA Kaito, SUTO Naoya, SEKI Hiroto, KAWAKAMI Takuya, Kentaro Nagamatsu, 高林圭佑, 小林洋平, 山口誠, Yuusuke Takashima, Yoshiki Naoi and Takuro Tomita : p型窒化ガリウム上金属電極へのピコ秒レーザー照射の影響, 令和6年電気学会全国大会, 2-079, Mar. 2024.
14.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Polarization tunable structural color from Ni-subwavelength grating/SiO2/Ni, 第84回応用物理学会秋季学術講演会, 22p-P04-14, Sep. 2023. (Keyword) nanophotonics
15.	Shunsuke Furuta, Kentaro Nagamatsu, Masanobu Haraguchi, Yoshiki Naoi and Yuusuke Takashima : Visible to near-infrared broadband absorber with multilayer including ultra-thin Fe film by complex Fresnel reflection, 第84回応用物理学会秋季学術講演会, 21a-A309-4, Sep. 2023. (Keyword) nanophotonics
16.	Yua Okano, Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Improvement of resonant sharpness in deep ultraviolet region using high aspect ratio AlN subwavelength grating, 2023年度応用物理・物理系学会中国四国支部合同学術講演会, Ep-6, Jul. 2023. (Keyword) nanophotonics
17.	Shunsuke Furuta, Kentaro Nagamatsu, Yoshiki Naoi and Yuusuke Takashima : Narrowing the absorption spectrum of multilayer structure by large complex Fresnel multiple reflection, 2023年度応用物理・物理系学会中国四国支部合同学術講演会, Ep-5, Jul. 2023. (Keyword) nanophotonics
18.	髙柳祐介, ATSUSHI Tomita, Kohki Fujii, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 窒化処理した高温成長AlNにおける極性反転, 2023年度応用物理・物理系学会中国四国支部合同学術講演会, Jul. 2023.
19.	MATSUBARA Yuto, ATSUSHI Tomita, Kohki Fujii, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 高オフ角サファイア基板上AlNのステップバンチング低減技術, 2023年度応用物理・物理系学会中国四国支部合同学術講演会, Jul. 2023.
20.	富田敦之, 宮川拓己, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 超高温MOVPEを用いたAlGaN成長, 第70回応用物理学会春季学術講演会, Mar. 2023.
21.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Investigation for high sensitivity refractive index sensing by multilayer containing highly lossy material, 第70回応用物理学会春季学術講演会, 17p-A305-14, Mar. 2023. (Keyword) nanophotonics
22.	Masaharu Kato, Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Refractive index sensor by using the combination of high contrast gratings operating at two wavelengths, レーザー学会学術講演会第43回年次大会, P01-20p-P-19, Jan. 2023. (Keyword) nanophotonics
23.	ATSUSHI Tomita, Takumi Miyagawa, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 気相反応抑制下におけるAlN高温成長の最適化のためのV/III比依存性, 第14回ナノ構造エピタキシャル成長講演会, Fr-P19, Nov. 2022.
24.	Kentaro Nagamatsu : 有機金属気相成長法による高温AlN成長, 第14回ナノ構造エピタキシャル成長講演会, Fr-I04, Nov. 2022.
25.	Atsuki Sasada, Takumi Miyagawa, Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Highly Reflective Reflector with Airgap High-Contrast Subwavelength Grating for Deep Ultraviolet Wavelength, 日本光学会年次学術講演会 Optics & Photonics Japan 2022, Vol.P15, Nov. 2022. (Keyword) nanophotonics
26.	Takehiro Nezu, Takumi Miyagawa, Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : Highly sensitive refractive index sensor with double-layer subwavelength gratings operating ultraviolet region, 日本光学会年次学術講演会 Optics & Photonics Japan 2022, Vol.P14, Nov. 2022. (Keyword) nanophotonics
27.	富田敦之, 津田翔太, Takumi Miyagawa, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 低オフ角サファイヤ基板を用いた高温AIN成長におけるV/Ⅲ比依存性, 第69回応用物理学会春季学術講演会, 25a-E203-3, Mar. 2022.
28.	宮川拓己, 津田翔太, Atsushi Tomita, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 高温有機金属気相成長法におけるAlNの特異的なステップバンチング, 第69回応用物理学会春季学術講演会, 25a-E203-2, Mar. 2022.
29.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : 高屈折率を有するTiO2極薄膜を用いた深紫外光吸収体, 第69回応用物理学会春季学術講演会, 24a-E303-9, Mar. 2022.
30.	Atsushi Tomita, Shota Tsuda, Takumi Miyagawa, Yuusuke Takashima, Yoshiki Naoi, 平山秀樹 and Kentaro Nagamatsu : 気相反応を制御したMOVPEにおけるAlNのV/III比依存性, 第50回日本結晶成長学会, Oct. 2021.
31.	Atsushi Tomita, 津田翔太, 宮川拓己, Yuusuke Takashima, Yoshiki Naoi, 平山秀樹 and Kentaro Nagamatsu : 気相反応を抑制したMOVPEにおけるAlNのV/Ⅲ比依存性, 第50回結晶成長国内会議(JCCG-50), 27p-A12, Oct. 2021.
32.	Yuusuke Takashima, Atsuki Sasada, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : AlNサブ波長回折格子を用いた深紫外ミラーの広帯域化, 第82回応用物理学会秋季学術講演会, 13a-N324-3, Sep. 2021.
33.	津田翔太, 宮川拓己, Atsushi Tomita, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : インバージョンドメインの抑制による高品質AlN成長手法の確立, 第82回応用物理学会秋季学術講演会, 13p-N101-10, Sep. 2021.
34.	Shota Tsuda, Takumi Miyagawa, Atsushi Tomita, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 極性制御による高品質AlN成長手法の確立, 応用物理学会中四国支部若手研究会, Aug. 2021.
35.	Atsushi Tomita, Shota Tsuda, Reiya Aono, Takumi Miyagawa, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 気相反応を抑制した高温MOVPEにおけるV/III比依存性, 応用物理学会中四国支部若手研究会, Aug. 2021.
36.	Takeo Minamikawa, Takaaki Koma, 鈴木昭浩, Kentaro Nagamatsu, Takeshi Yasui, Koji Yasutomo and Masako Nomaguchi : 深紫外LEDを用いた新型コロナウイルスの不活化, 電気学会光・量子デバイス研究会「パワー光源システム技術研究会」, Jul. 2021.
37.	宮川拓己, 津田翔太, 青野零弥, 揚田侑哉, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : AlNの高流速成長における成長メカニズム, 第68回応用物理学会春季学術講演会, 19p-Z27-13, Mar. 2021.
38.	津田翔太, 青野零弥, 揚田侑哉, 宮川拓己, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : AlNテンプレート上高温AlN結晶成長, 第68回応用物理学会春季学術講演会, 19p-Z27-3, Mar. 2021.
39.	Kentaro Nagamatsu, 津田翔太, 青野零弥, 宮川拓己, 揚田侑哉, 平山秀樹, Yuusuke Takashima and Yoshiki Naoi : 高温有機金属気相成長装法におけるAlN成長の気相反応抑制, 第68回応用物理学会春季学術講演会, 19p-Z27-14, Mar. 2021.
40.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : TiO2メタ周期構造を表面に有するAlGaN系深紫外発光ダイオードのコリメート特性, 第68回応用物理学会春季学術講演会, 19a-Z08-7, Mar. 2021.
41.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : 構造高さを変調したTiO2メタ表面による集光紫外発光ダイオードの提案, 日本光学会年次学術講演会Optics & Photonics Japan 2020, 17pC4, Nov. 2020.
42.	Reiya Aono, Yuusuke Takashima, Yoshiki Naoi, Takeshi Yasui and Kentaro Nagamatsu : 紫外光LEDの大気中における光減衰に関する研究, 第67回応用物理学会春季学術講演会予稿集, 12p-B409-8, Mar. 2020.
43.	Kentaro Nagamatsu and 平山秀樹 : AlGaN深紫外LEDの課題と最近の進展, ポストLEDフォトニクス研究所公開シンポジウム2019, Oct. 2019.
44.	上杉謙次郎, 林侑介, 正直花奈子, Kentaro Nagamatsu and 三宅秀人 : 講演奨励賞受賞記念講演深紫外発光素子応用に向けたスパッタ成膜AlNテンプレートの転位密度低減, 第66回応用物理学会春季学術講演会, Mar. 2019.
45.	上杉謙次郎, 林侑介, 正直花奈子, Kentaro Nagamatsu, 吉田治正 and 三宅秀人 : 高温アニールしたAlNのクラック抑制と高品質化, 第79回応用物理学会秋季学術講演会, Sep. 2018.
46.	Kentaro Nagamatsu, 上杉謙次郎, 三宅秀人 and 吉田治正 : 歪緩和による深紫外LEDの発光効率改善, 第79回応用物理学会秋季学術講演会, Sep. 2018.
47.	Kentaro Nagamatsu, 上杉謙次郎, 正直花奈子, 吉田治正 and 三宅秀人 : スパッタ法AlN膜の高温アニールとその基板上への AlGaN深紫外LED作製, 第79回応用物理学会秋季学術講演会, Sep. 2018.
48.	田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : 多光子 PL 顕微鏡による窒化ガリウム中転位の三次元観察, 日本結晶成長学会ナノ構造・エピタキシャル成長分科会2018年講演会第10回ナノ構造・エピタキシャル成長講演会, Jul. 2018.
49.	安藤悠人, Kentaro Nagamatsu, 田中敦之, 宇佐美茂佳, 出来真斗, 久志本真希, 新田州吾, 本田善央 and 天野浩 : m 面 GaN 基板上 SBD における障壁高さの金属仕事関数依存性, 日本結晶成長学会ナノ構造・エピタキシャル成長分科会2018年講演会第10回ナノ構造・エピタキシャル成長講演会, Jul. 2018.
50.	上杉謙次郎, 正直花奈子, 林侑介, 肖世玉, Kentaro Nagamatsu, 吉田治正 and 三宅秀人 : 6H-SiC基板上におけるAlN周期構造の作製と評価, 日本結晶成長学会ナノ構造・エピタキシャル成長分科会2018年講演会第10回ナノ構造・エピタキシャル成長講演会, Jul. 2018.
51.	田中敦之, 宇佐美茂佳, 安藤悠人, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : ∼格子欠陥はどこまで制御できるのか:先端評価と機能探索∼, 第65回応用物理学会春季学術講演会, Mar. 2018.
52.	田中大暉, Kentaro Nagamatsu, 山田永, 山田寿一, 熊谷義直, 新田州吾, 本田善央, 清水三聡 and 天野浩 : HVPE法によるAlGaNの薄膜成長, 第65回応用物理学会春季学術講演会, Mar. 2018.
53.	叶正, 新田州吾, Kentaro Nagamatsu, 本田善央 and 天野浩 : 高分解能質量分析によるⅢ族窒化物半導体気相成長のためのアンモニア分解及び反応の解析, 第65回応用物理学会春季学術講演会, Mar. 2018.
54.	大河内勇斗, 関口一樹, 長川健太, 洗平昌晃, Kentaro Nagamatsu, 新田州吾, 本田善央, 天野浩 and 白石賢二 : h-BN MOVPE中における気相反応プロセスの理論的検討, 第65回応用物理学会春季学術講演会, Mar. 2018.
55.	出来真斗, 曾根和詩, Kentaro Nagamatsu, 田中敦之, 久志本真希, 新田州吾, 本田善央 and 天野浩 : GaN表面への酸化プロセスがALD-Al2O3/GaN界面の電気特性に与える影響, 第65回応用物理学会春季学術講演会, Mar. 2018.
56.	宇佐美茂佳, 菅原義弘, 姚永昭, 石川由加里, 間山憲仁, 戸田一也, 安藤悠人, 田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : 3DAP および LACBED 法による GaN 自立基板上 pn ダイオードのリークの起源調査, 第65回応用物理学会春季学術講演会, Mar. 2018.
57.	宇佐美茂佳, 福島颯太, 安藤悠人, 田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : GaN 自立基板上 pn ダイオード逆方向リーク電流の成長条件依存性, 第65回応用物理学会春季学術講演会, Mar. 2018.
58.	安藤悠人, Kentaro Nagamatsu, 田中敦之, 宇佐美茂佳, バリーウスマン1, 出来真斗, 久志本真希, 新田州吾, 本田善央 and 天野浩 : m面GaN基板上SBDにおける障壁高さの金属仕事関数依存性, 第65回応用物理学会春季学術講演会, Mar. 2018.
59.	河野司, 久志本真希, Kentaro Nagamatsu, 新田州吾, 本田義央 and 天野浩 : -C面GaN基板上のGaNのMOVPE成長における酸素低減の研究, 電子情報通信学会名古屋工業大学, Nov. 2017.
60.	Kentaro Nagamatsu, Shugo Nitta, Zheng Ye, Hirofumi Nagao, Shinichi Miki, Yoshio Honda and Hiroshi Amano : In-situ gas monitoring in metalorganic vapor phase epitaxy reactor during GaN growth bymulti-turn Time-of-flight mass spectrometry, 第 15 回赤﨑記念研究センターシンポジウム「窒化物半導体研究の新展開:新規デバイスの創出をめざして」, Nov. 2017.
61.	安藤悠人, Kentaro Nagamatsu, 田中敦之, 宇佐美茂佳, バリーウスマン1, 出来真斗, 久志本真希, 新田州吾, 本田善央 and 天野浩 : オフ角の異なるm 面GaN 基板上Si ドープ厚膜SBD, 第78回応用物理学会秋季学術講演会, Sep. 2017.
62.	宇佐美茂佳, 福島颯太, 安藤悠人, 田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : 転位密度の異なるGaN自立基板上PNダイオードのキラー転位解析, 第78回応用物理学会秋季学術講演会, Sep. 2017.
63.	白石賢二, 関口一樹, 長川健太, 白川裕規, 川上賢人, 山本芳裕, 洗平昌晃, Kentaro Nagamatsu, 新田州吾, 岡本直也, 芳松克則, 寒川義裕, 柿本浩一 and 天野浩 : エピタキシャル成長のマルチフィジックスシミュレーションの現状, 第64回応用物理学会春季学術講演会, Mar. 2017.
64.	田中敦之, バリー 1 オースマネー, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : m面GaN SBDの漏れ電流のファセット依存性, 第64回応用物理学会春季学術講演会, Mar. 2017.
65.	曾根和詩, 松下淳矢, 安藤悠人, Kentaro Nagamatsu, 田中敦之, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : O2プラズマ処理および O3酸化処理を行った Al 2O3/GaN /GaN 構造の界面準位密度評価, 第64回応用物理学会春季学術講演会, Mar. 2017.
66.	宇佐美茂佳, 安藤悠人, 田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : GaN自立基板上PNダイオードの逆方向リークと転位の関係, 第64回応用物理学会春季学術講演会, Mar. 2017.
67.	叶正, Kentaro Nagamatsu, 新田州吾, 本田善央 and 天野浩 : MOHVPE法における中間反応, 第64回応用物理学会春季学術講演会, Mar. 2017.
68.	安藤悠人, 小倉昌也, 松下淳矢, 宇佐美茂佳, 田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : 2次元正孔ガスを用いたコレクタトップ縦型GaN-HBTの作製, 第64回応用物理学会春季学術講演会, Mar. 2017.
69.	宇佐美茂佳, 安藤悠人, 田中敦之, Kentaro Nagamatsu, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : GaN 自立基板上PIN ダイオードにおける順方向発光パターン解析, 第77回応用物理学会秋季学術講演会, Sep. 2016.
70.	宮越亮輔, 劉志彬, 山本哲也, Kentaro Nagamatsu, 新田州吾, 本田善央 and 天野浩 : レーザ散乱光強度その場観察によるInGaN 成長モードの解析, 第77回応用物理学会秋季学術講演会, Sep. 2016.
71.	松下淳矢, Kentaro Nagamatsu, Yang Xu, 田中敦之, 久志本真希, 出来真斗, 新田州吾, 本田善央 and 天野浩 : 窒化ホウ素を用いたGaN -MIS キャパシタの作製と電気特性評価, 第77回応用物理学会秋季学術講演会, Sep. 2016.
72.	山本哲也, 田村彰, Kentaro Nagamatsu, 新田州吾, 本田善央 and 天野浩 : レーザ散乱を用いたInGaN結晶成長表面粗さ回復の観察, 第63回応用物理学会春季学術講演会, Mar. 2016.
73.	川口真生, 今藤修, Kentaro Nagamatsu, 山中一彦, 瀧川信一 and 片山琢磨 : 長共振器型窒化物系面発光レーザの設計と発振特性, 第76回応用物理学会秋季学術講演会, Sep. 2015.
74.	永田賢昌, 飯田大輔, Kentaro Nagamatsu, 竹田健一郎, 松原哲也, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : GaInNの加圧MOVPEにおける熱力学解析, 電子情報通信学会徳島大学, Nov. 2009.
75.	永田賢吾, 市川友紀, 竹田健一郎, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : 酸素雰囲気中での活性化アニールによる紫外発光素子の高効率化, 電子情報通信学会徳島大学, Nov. 2009.
76.	永田賢吾, 竹田健一郎, 市川友紀, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : 酸素雰囲気中でのp 型AlGaN の活性化による高出力AlGaN/GaN 紫外LED, 第70回応用物理学会学術講演会, Sep. 2009.
77.	野中健太朗, 浅井俊晶, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : Mg-doped AlN下地層を用いた低転位AlGaNの微細構造観察, 第70回応用物理学会学術講演会, Sep. 2009.
78.	浅井俊晶, 野中健太朗, 伴和仁, 永田賢昌, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : Mg-doped AlN下地層によるAlGaNの低転位化の機構, 第70回応用物理学会学術講演会, Sep. 2009.
79.	Kentaro Nagamatsu, 竹田健一郎, 飯田大輔, 永田賢昌, 浅井俊晶, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : AlGaNの原子層エピタキシャル成長, 第70回応用物理学会学術講演会, Sep. 2009.
80.	永田賢昌, 飯田大輔, Kentaro Nagamatsu, 松原哲也, 竹田健一郎, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : 高圧MOVPE法を用いたGaInN成長, 第70回応用物理学会学術講演会, Sep. 2009.
81.	永田賢昌, 飯田大輔, Kentaro Nagamatsu, 松原哲也, 竹田健一郎, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : 加圧MOVPEによる高速バルブスイッチング技術を用いたAlGaNの高品質化, 第70回応用物理学会学術講演会, Sep. 2009.
82.	Kentaro Nagamatsu, 浅井俊晶, 竹田健一郎, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : AlGaN中のMgの活性化エネルギー(II), 第56回応用物理学関係連合講演会, Mar. 2009.
83.	永田賢吾, 竹田健一郎, Kentaro Nagamatsu, 都築宏俊, 岩谷素顕, 上山智, 天野浩 and 赤崎勇 : 活性化アニールによるp型Al0.17Ga0.83Nの正孔濃度と接触比抵抗の評価, 第56回応用物理学関係連合講演会, Mar. 2009.
84.	福井一俊, 伊藤智治, 鈴木将孝, 岸田正明, Kentaro Nagamatsu, 天野浩 and 平山秀樹 : AlN のバンド構造と偏光特性, 第69回応用物理学会学術講演会, Sep. 2008.
85.	鈴木将孝, 澤井駿, 福井一俊, Kentaro Nagamatsu and 天野浩 : Mg-doped p-AlGaN混晶の発光スペクトルの温度依存性, 第69回応用物理学会学術講演会, Sep. 2008.
86.	福井一俊, 伊藤智治, 鈴木将孝, 岸田正明, Kentaro Nagamatsu, 天野浩 and 平山秀樹 : AlN のバンド構造と偏光特性, 第69回応用物理学会学術講演会, Sep. 2008.
87.	鈴木将孝, 澤井駿, 福井一俊, Kentaro Nagamatsu and 天野浩 : Mg-doped p-AlGaN混晶の発光スペクトルの温度依存性, 第69回応用物理学会学術講演会, Sep. 2008.
88.	竹田健一郎, 森史明, 小木曽裕二, 森俊晶, 浅井俊晶, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : 周期溝下地結晶を用いたAl0.5Ga0.5Nの低転位化, 第69回応用物理学会学術講演会, Sep. 2008.
89.	森俊晶, 浅井俊晶, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : 溝加工したAlN上AlGaNの転位解析, 電子情報通信学会名古屋工業大学, May 2008.
90.	Kentaro Nagamatsu, 岡田成仁, 井村将隆, 岩谷素顕, 上山智, 天野浩 and 赤﨑勇 : AlGaN中のMgの活性化エネルギー, 第55回応用物理学関係連合講演会, Mar. 2008.
91.	天野浩, Kentaro Nagamatsu, 飯田大輔, 竹田健一郎, 都築宏俊, 早川武雅, 岩谷素顕, 上山智 and 赤﨑勇 : シミュレータを用いた窒化物半導体光デバイスの動作シミュレーションおよび実際との比較, 日本学術振興会ワイドギャップ半導体光・電子デバイス第162委員会2008, 2008.
92.	天野浩, Kentaro Nagamatsu, 飯田大輔, 竹田健一郎, 都築宏俊, 早川武雅, 岩谷素顕, 上山智 and 赤﨑勇 : シミュレータを用いた窒化物半導体光デバイスの動作シミュレーションおよび実際との比較, 日本学術振興会ワイドギャップ半導体光・電子デバイス第162委員会2008, 2008.
93.	飯田一喜, 渡邉浩嵩, 竹田健一郎, 住井隆文, 永井哲也, Kentaro Nagamatsu, 岡田成仁, クリシュナンバラクリシュナン, 岩谷素顕, 上山智, 天野浩, 赤﨑勇 and 坂東章 : 低転位化によるAlGaN系紫外発光素子の高効率化(III), 第54回応用物理学関係連合講演会, Mar. 2007.
94.	飯田一喜, 渡邉浩嵩, 竹田健一郎, 住井隆文, 永井哲也, Kentaro Nagamatsu, 岡田成仁, バラクリシュナンクリシュナン, 岩谷素顕, 上山智, 天野浩, 赤﨑勇 and 坂東章 : 低転位化によるAlGaN系紫外発光素子の高効率化(III), 電子情報通信学会京都大学, Oct. 2006.
95.	三島俊介, Kentaro Nagamatsu, 本塩彰, 三宅泰人, 浅井利浩, 飯田一喜, 川島毅, 岩谷素顕, 上山智, 天野浩 and 赤崎勇 : 顕微ラマン分光法によるNitride-LEDの動作時におけるGaN層の温度分布解析, 第66回応用物理学会学術講演会, Sep. 2005.
96.	Kentaro Nagamatsu, 岡留由真, 古川寛子, 土屋陽祐, 浅井利浩, 三島俊介, 本塩彰, 岩谷素顕, 上山智, 天野浩 and 赤崎勇 : サファイアR面基板上ナイトライドLEDの特性, 第66回応用物理学会学術講演会, Sep. 2005.

Et cetera, Workshop:

1.	藤井滉樹, Takumi Miyagawa, ATSUSHI Tomita, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : X線回折を用いたステップバンチングの発生オフ角評価, 応用物理学会中四国支部・若手半導体研究会, Aug. 2022.
2.	Masaki Fujita, Takumi Miyagawa, ATSUSHI Tomita, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : MOVPE 超高温成長中断アニーリングによる A lN 転位低減手法, 応用物理学会中四国支部・若手半導体研究会, Aug. 2022.
3.	Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : 高屈折率ナノ構造による深紫外∼可視域での発光およびセンシングデバイス, 第173回ラドテック研究会講演会, 2, Nov. 2021.
4.	Atsushi Tomita, 津田翔太, 青野零弥, 宮川拓己, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 気相反応を抑制した高温MOVPEにおけるV/Ⅲ比依存性, 2021年度応用物理学会中国四国支部若手半導体研究会, 1-11, Aug. 2021.
5.	津田翔太, 宮川拓己, Atsushi Tomita, 平山秀樹, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 極性制御による高品質AlN成長手法の確立, 2021年度応用物理学会中国四国支部若手半導体研究会, 1-12, Aug. 2021.
6.	揚田侑哉, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : AlN高温成長での面内膜厚分布の改善, LED総合フォーラム2021in徳島, P-17, Feb. 2021.
7.	杉本健太, Yuusuke Takashima, Kentaro Nagamatsu, Masanobu Haraguchi and Yoshiki Naoi : サブ波長周期電極を有する紫外発光ダイオード偏光特性に対する電極材料の影響, LED総合フォーラム2021in徳島, P-10, Feb. 2021.
8.	Reiya Aono, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 深紫外LEDの大気中における光減衰に関する研究, LED総合フォーラム2020in徳島, P-16, Feb. 2020.
9.	村上堅也, Yoshiki Naoi, Yuusuke Takashima and Kentaro Nagamatsu : 深紫外LEDの発光層温度予測と寿命の関係, 徳島大学ポストLEDフォトニクス公開シンポジウム2019, P-20, Oct. 2019.
10.	青野零弥, Yuusuke Takashima, Yoshiki Naoi and Kentaro Nagamatsu : 次世代癌治療用深紫外スポットLEDの開発, 徳島大学ポストLEDフォトニクス公開シンポジウム2019, P-19, Oct. 2019.
11.	津田翔太, Yoshiki Naoi, Yuusuke Takashima and Kentaro Nagamatsu : 次世代殺菌浄水システム, 徳島大学ポストLEDフォトニクス公開シンポジウム2019, P-18, Oct. 2019.
12.	河野司, 久志本真希, Kentaro Nagamatsu, 新田州吾, 本田善央 and 天野浩 : -c 面 GaN 基板上の GaN の MOVPE 成長における酸素低減の研究 (電子デバイス), IEICE Technical Report, Vol.117, No.331, 19-22, Nov. 2017. (Summary) GaN epitaxial layer grown on -c plane substrate by MOVPE has a smaller amount of carbon incorporation that compensates electrons than GaN on the + c plane substrate, making it possible to control lower impurity concentration in the drift layer of power device. Therefore, there is a possibility of realizing a high voltage device. However, there is a problem that the amount of oxygen incorporation is as high as 1018 cm-3 or more, therefore the depletion layer does not extend and the operating voltage becomes low. Therefore, in this research, we tried to grow at higher temperature to reduce oxygen concentration. As a result, reduction of luminescence caused by oxygen can be confirmed from PL measurement.
13.	Kentaro Nagamatsu : 3族窒化物半導体紫外発光素子の高効率化のための要素技術に関する研究, CiNii 国立情報学研究所学術情報ナビゲータ, Mar. 2010.
14.	永田賢吾, 市川友紀, 竹田健一郎, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤崎勇 : 酸素雰囲気中での活性化アニールによる紫外発光素子の高効率化, IEICE Technical Report, Vol.109, No.289, 75-80, Nov. 2009. (Summary) Activation annealing of Mg-doped p-type Al0.17Ga0.83N in different gases was conducted. The hole concentration in Al0.17Ga0.83N annealed in oxygen flow is higher than those annealed in nitrogen or air. A hole concentration of 1.3×1016 cm-3 at room temperature was achieved by annealing in oxygen flow at 900 oC. We also confirmed the effect of activation annealing in oxygen flow on the performance of UV LED. At a DC current of 100 mA, the output power of the LED annealed in oxygen flow at 900 oC is 4 times higher than that of the LED annealed in nitrogen flow at 800 oC.
15.	永田賢昌, 飯田大輔, Kentaro Nagamatsu, 竹田健一郎, 松原哲也, 岩谷素顕, 上山智, 天野浩 and 赤崎勇 : GaInN の加圧 MOVPE における熱力学解析, IEICE Technical Report, Vol.109, No.288, 55-58, Nov. 2009. (Summary) High In content GaInN films are promising for many applications such as multi-junction tandem photovoltaic cells, high power heterostructured field-effect transistors, high-brightness green light-emitting diodes, etc. Up to now, growth temperature for high In composition GaInN films should be lower than that of GaN. It is desirable to grow GaInN at higher temperature to achieve high quality and low residual impurities. It is possible to grow GaInN at higher temperature under higher pressure. This paper reports GaInN growth at raised pressure by MOVPE and these thermodynamic aspects.
16.	森俊晶, 浅井俊晶, Kentaro Nagamatsu, 岩谷素顕, 上山智, 天野浩 and 赤崎勇 : 溝加工した AlN 上 AlGaN の転位解析, IEICE Technical Report, Vol.108, No.36, 57-60, May 2008.
17.	渡邉浩崇, 飯田一喜, 竹田健一郎, Kentaro Nagamatsu, 住井隆文, 永井哲也, バラクリッシュナンクリッシュナン, 岩谷素顕, 上山智, 天野浩, 赤崎勇 and 坂東章 : 様々な基板上への紫外発光素子の作製と評価, IEICE Technical Report, Vol.106, No.269, 87-92, Oct. 2006.

Patent:

1.	Shugo Nitta, Yoshio Honda, Kentaro Nagamatsu, Hiroshi Amano and Naoki Fujimoto : VAPOR PHASE EPITAXIAL GROWTH DEVICE, PCT I JP2018/033324 (Mar. 2020).
2.	Kentaro Nagamatsu, 吉田治正 and 三宅秀人 : 半導体基板および半導体基板の製造方法, 2018-155448 (Aug. 2018), 2020-29383 (Feb. 2020), .
3.	新田州吾, Kentaro Nagamatsu, 天野浩, 三木伸一 and 長尾博文 : 気相成長装置, 2017-241860 (Dec. 2017), 2019-110197 (Jul. 2019), .
4.	新田州吾, 本田善央, Kentaro Nagamatsu, 天野浩 and 藤本直樹 : 気相成長装置, 2017-183987 (Sep. 2017), 2019-059636 (Apr. 2019), .

Grants-in-Aid for Scientific Research (KAKEN Grants Database @ NII.ac.jp)

Study on deep ultraviolet LEDs with the wavelength of 220nm by Jet gas stream MOVPE (Project/Area Number: 23K23241 )
Low dislocation AlN growth by super high temperature MOVPE in jet engine model (Project/Area Number: 20K21006 )
Search by Researcher Number (40774378)

Associate Professor : Nagamatsu, Kentaro

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Grants-in-Aid for Scientific Research (KAKEN Grants Database @ NII.ac.jp)