Maki Sugai
Toshiba
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Publication
Featured researches published by Maki Sugai.
Proceedings of SPIE | 2012
Yoshiyuki Harada; Toshiki Hikosaka; Shigeya Kimura; Maki Sugai; Hajime Nago; Koichi Tachibana; Naoharu Sugiyama; Shinya Nunoue
The contribution of reduction of threading dislocation densities (TDDs) to optical properties is investigated for InGaN/GaN light-emitting diodes (LEDs) grown on sapphire substrate. The external quantum efficiency (EQE) curves depending on the TDDs are discussed both theoretically and experimentally. At the current density of <20 A/cm2, the EQE increases with decreasing the edge-type TDD from 5 e8/cm2 to 2 e8/cm2. The current density at the maximum EQE shifts to lower value as the edge-type TDD decreases, whereas the EQE presents no remarkable difference in the highercurrent density range irrespective of the TDD. According to the rate equation (ABC) model, the peak shift reflects the Shockley-Read-Hall non-radiative process (A coefficient). Analysis of the photoluminescence (PL) decay and the dependence of integrated PL intensity on excitation power reveals that the threading dislocations act as non-radiative recombination centers in the multiple quantum well active region. The TDD of <2 e8/cm2 is required for highly efficient blue LEDs operating at current density of around 15 A/cm2, whereas the TDD of <5 e8/cm2 in required for the LEDs operating at around 50 A/cm2.
international semiconductor laser conference | 2008
Shinji Saito; Yasushi Hattori; Maki Sugai; Yoshiyuki Harada; H. Jongil; Shinya Nunoue
GaN-based laser diodes (LDs) with a slope efficiency of 2.6 W/A are presented. The white light source was fabricated by using 405 nm LDs and phosphors. The luminous flux was estimated to be 200 lm.
Archive | 2005
Takahiro Sato; Shinji Saito; Shinya Nunoue; Yasushi Hattori; Maki Sugai
Archive | 2014
Toshiki Hikosaka; Yoshiyuki Harada; Maki Sugai; Shinya Nunoue
Archive | 2012
Toshiki Hikosaka; Yoshiyuki Harada; Maki Sugai; Shinya Nunoue
Archive | 2012
Koichi Tachibana; Hisashi Yoshida; Hiroshi Ono; Hajime Nago; Yoshiyuki Harada; Toshiki Hikosaka; Maki Sugai; Toshiyuki Oka; Shinya Nunoue
Archive | 2011
Koichi Tachibana; 浩一 橘; Gakushi Yoshida; 学史 吉田; Hiroshi Ono; 浩 大野; Hajime Nago; 肇 名古; Yoshiyuki Harada; 佳幸 原田; Toshiteru Hikosaka; 年輝 彦坂; Maki Sugai; 麻希 菅井; Toshiyuki Oka; 俊行 岡; Shinya Nunoue; 真也 布上
Archive | 2015
Jongil Hwang; Shinji Saito; Maki Sugai; Rei Hashimoto; Yasushi Hattori; Masaki Tohyama; Shinya Nunoue
Archive | 2012
Toshiki Hikosaka; Yoshiyuki Harada; Maki Sugai; Shinya Nunoue
Archive | 2008
Yasushi Hattori; Shinji Saito; Shinya Nunoue; Eiji Muramoto; Koichi Tachibana; Saori Abe; J. I. Hwang; Maki Sugai