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Journal Articles

Quantum efficiency characteristics of low-threading-dislocation-density InGaN photocathode grown on GaN substrate

Mikiya Idei, Daiki Sato, Atsushi Koizumi, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano
Journal: Journal of Vacuum Science & Technology B
J. Vac. Sci. Technol. B 43, 032202 (2025)
https://doi.org/10.1116/6.0004199
Published: March 2025
View articletitled, Quantum efficiency characteristics of low-threading-dislocation-density InGaN photocathode grown on GaN substrate
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Journal Articles

Time response measurement of pulsed electron beam from InGaN photocathode

Daiki Sato, Haruka Shikano, Atsushi Koizumi, Tomohiro Nishitani
Journal: Journal of Vacuum Science & Technology B
J. Vac. Sci. Technol. B 40, 064204 (2022)
https://doi.org/10.1116/6.0002122
Published: November 2022
View articletitled, Time response measurement of pulsed electron beam from InGaN photocathode
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Journal Articles

Scanning electron microscope imaging by selective e-beaming using photoelectron beams from semiconductor photocathodes

Tomohiro Nishitani, Yuta Arakawa, Shotaro Noda, Atsushi Koizumi, Daiki Sato, Haruka Shikano, Hokuto Iijima, Yoshio Honda, Hiroshi Amano
Journal: Journal of Vacuum Science & Technology B
J. Vac. Sci. Technol. B 40, 064203 (2022)
https://doi.org/10.1116/6.0002111
Published: November 2022
View articletitled, Scanning electron microscope imaging by selective e-beaming using photoelectron beams from semiconductor photocathodes
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Journal Articles

Dependence of electron emission current density on excitation power density from Cs/O-activated negative electron affinity InGaN photocathode

Atsushi Koizumi, Daiki Sato, Haruka Shikano, Hokuto Iijima, Tomohiro Nishitani
Journal: Journal of Vacuum Science & Technology B
J. Vac. Sci. Technol. B 40, 062202 (2022)
https://doi.org/10.1116/6.0002124
Published: October 2022
View articletitled, Dependence of electron emission current density on excitation power density from Cs/O-activated negative electron affinity InGaN photocathode
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Journal Articles

Multiple electron beam generation from InGaN photocathode

Daiki Sato, Haruka Shikano, Atsushi Koizumi, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano
Journal: Journal of Vacuum Science & Technology B
J. Vac. Sci. Technol. B 39, 062209 (2021)
https://doi.org/10.1116/6.0001272
Published: November 2021
View articletitled, Multiple electron beam generation from InGaN photocathode
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Journal Articles

Analysis of negative electron affinity InGaN photocathode by temperature-programed desorption method

Masahiro Kashima, Daiki Sato, Atsushi Koizumi, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano, Hokuto Iijima, Takashi Meguro
Journal: Journal of Vacuum Science & Technology B
J. Vac. Sci. Technol. B 36, 06JK02 (2018)
https://doi.org/10.1116/1.5048061
Published: October 2018
View articletitled, Analysis of negative electron affinity InGaN photocathode by temperature-programed desorption method
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Journal Articles

Control of GaN facet structures through Eu doping toward achieving semipolar { 1 1 ¯ 01 } and { 2 2 ¯ 01 } InGaN/GaN quantum wells

Takanori Kojima, Shota Takano, Ryosuke Hasegawa, Dolf Timmerman, Atsushi Koizumi, Mitsuru Funato, Yoichi Kawakami, Yasufumi Fujiwara
Journal: Applied Physics Letters
Appl. Phys. Lett. 109, 182101 (2016)
https://doi.org/10.1063/1.4965844
Published: October 2016
View articletitled, Control of GaN facet structures through Eu doping toward achieving semipolar { 1 1 ¯ 01 } and { 2 2 ¯ 01 } InGaN/GaN quantum wells
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Journal Articles

Substantial enhancement of red emission intensity by embedding Eu-doped GaN into a microcavity

Tomohiro Inaba, Dong-gun Lee, Ryuta Wakamatsu, Takanori Kojima, Brandon Mitchell, Antonio Capretti, Tom Gregorkiewicz, Atsushi Koizumi, Yasufumi Fujiwara
Journal: AIP Advances
AIP Advances 6, 045105 (2016)
https://doi.org/10.1063/1.4946849
Published: April 2016
View articletitled, Substantial enhancement of red emission intensity by embedding Eu-doped GaN into a microcavity
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Journal Articles

Resonant energy transfer between Eu luminescent sites and their local geometry in GaN

Dolf Timmerman, Ryuta Wakamatsu, Kazuteru Tanaka, Dong-gun Lee, Atsushi Koizumi, Yasufumi Fujiwara
Journal: Applied Physics Letters
Appl. Phys. Lett. 107, 151107 (2015)
https://doi.org/10.1063/1.4933301
Published: October 2015
View articletitled, Resonant energy transfer between Eu luminescent sites and their local geometry in GaN
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Journal Articles

Three-dimensional spectrum mapping of bright emission centers: Investigating the brightness-limiting process in Eu-doped GaN red light emitting diodes

Masashi Ishii, Atsushi Koizumi, Yasufumi Fujiwara
Journal: Applied Physics Letters
Appl. Phys. Lett. 107, 082106 (2015)
https://doi.org/10.1063/1.4929531
Published: August 2015
View articletitled, Three-dimensional spectrum mapping of bright emission centers: Investigating the brightness-limiting process in Eu-doped GaN red light emitting diodes
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Journal Articles

Nanoscale determinant to brighten up GaN:Eu red light-emitting diode: Local potential of Eu-defect complexes

Masashi Ishii, Atsushi Koizumi, Yasufumi Fujiwara
Journal: Journal of Applied Physics
J. Appl. Phys. 117, 155307 (2015)
https://doi.org/10.1063/1.4918662
Published: April 2015
View articletitled, Nanoscale determinant to brighten up GaN:Eu red light-emitting diode: Local potential of Eu-defect complexes
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Journal Articles

Unique properties of photoluminescence excitation spectra in a Eu-doped GaN epitaxial film

Masaaki Nakayama, Satoshi Nakamura, Hideo Takeuchi, Atsushi Koizumi, Yasufumi Fujiwara
Journal: Applied Physics Letters
Appl. Phys. Lett. 106, 012102 (2015)
https://doi.org/10.1063/1.4905309
Published: January 2015
View articletitled, Unique properties of photoluminescence excitation spectra in a Eu-doped GaN epitaxial film
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Journal Articles

Enhancement in light efficiency of a GaN:Eu red light-emitting diode by pulse-controlled injected charges

Masashi Ishii, Atsushi Koizumi, Yasufumi Fujiwara
Journal: Applied Physics Letters
Appl. Phys. Lett. 105, 171903 (2014)
https://doi.org/10.1063/1.4900840
Published: October 2014
View articletitled, Enhancement in light efficiency of a GaN:Eu red light-emitting diode by pulse-controlled injected charges
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Journal Articles

Discrimination between energy transfer and back transfer processes for GaAs host and Er luminescent dopants using electric response analysis

Masashi Ishii, Atsushi Koizumi, Yoshikazu Takeda, Yasufumi Fujiwara
Journal: Journal of Applied Physics
J. Appl. Phys. 115, 133510 (2014)
https://doi.org/10.1063/1.4870808
Published: April 2014
View articletitled, Discrimination between energy transfer and back transfer processes for GaAs host and Er luminescent dopants using electric response analysis
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Journal Articles

Luminescence properties of Eu-doped GaN under resonant excitation and quantitative evaluation of luminescent sites

Ryuta Wakamatsu, Dong-gun Lee, Atsushi Koizumi, Volkmar Dierolf, Yasufumi Fujiwara
Journal: Journal of Applied Physics
J. Appl. Phys. 114, 043501 (2013)
https://doi.org/10.1063/1.4816088
Published: July 2013
View articletitled, Luminescence properties of Eu-doped GaN under resonant excitation and quantitative evaluation of luminescent sites
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Journal Articles

Effect of thermal annealing on luminescence properties of Eu,Mg-codoped GaN grown by organometallic vapor phase epitaxy

Dong-gun Lee, Ryuta Wakamatsu, Atsushi Koizumi, Yoshikazu Terai, Jonathan D. Poplawsky, Volkmar Dierolf, Yasufumi Fujiwara
Journal: Applied Physics Letters
Appl. Phys. Lett. 102, 141904 (2013)
https://doi.org/10.1063/1.4800447
Published: April 2013
View articletitled, Effect of thermal annealing on luminescence properties of Eu,Mg-codoped GaN grown by organometallic vapor phase epitaxy
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Journal Articles

High-quality single crystalline NiO with twin phases grown on sapphire substrate by metalorganic vapor phase epitaxy

Kazuo Uchida, Ken-ichi Yoshida, Dongyuan Zhang, Atsushi Koizumi, Shinji Nozaki
Journal: AIP Advances
AIP Advances 2, 042154 (2012)
https://doi.org/10.1063/1.4769082
Published: November 2012
View articletitled, High-quality single crystalline NiO with twin phases grown on sapphire substrate by metalorganic vapor phase epitaxy
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Journal Articles

Temperature and doping dependencies of electrical properties in Al-doped 4 H - Si C epitaxial layers

Atsushi Koizumi, Jun Suda, Tsunenobu Kimoto
Journal: Journal of Applied Physics
J. Appl. Phys. 106, 013716 (2009)
https://doi.org/10.1063/1.3158565
Published: July 2009
View articletitled, Temperature and doping dependencies of electrical properties in Al-doped 4 H - Si C epitaxial layers
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Journal Articles

Li- and Er-codoped ZnO with enhanced 1.54 μ m photoemission

Zhen Zhou, Toshitaka Komori, Tatsuya Ayukawa, Hiroshi Yukawa, Masahiko Morinaga, Atsushi Koizumi, Yoshikazu Takeda
Journal: Applied Physics Letters
Appl. Phys. Lett. 87, 091109 (2005)
https://doi.org/10.1063/1.2035867
Published: August 2005
View articletitled, Li- and Er-codoped ZnO with enhanced 1.54 μ m photoemission
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Journal Articles

Terahertz radiation from Er,O‐codoped GaAs surface

Masato Suzuki, Kazuhiko Nakamura, Yasufumi Fujiwara, Atsushi Koizumi, Yoshikazu Takeda, Masayoshi Tonouchi
Journal: AIP Conference Proceedings
AIP Conf. Proc. 772, 131–132 (2005)
https://doi.org/10.1063/1.1994028
Published: June 2005
View articletitled, Terahertz radiation from Er,O‐codoped GaAs surface
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