High external quantum efficiency (10%) AlGaN-based deep-ultraviolet light-emitting diodes achieved by using highly reflective photonic crystal on p-AlGaN contact layer. (30th November 2017)

• Record Type: Journal Article
• Authors: Kashima, Yukio; Maeda, Noritoshi; Matsuura, Eriko; Jo, Masafumi; Iwai, Takeshi; Morita, Toshiro; Kokubo, Mitsunori; Tashiro, Takaharu; Kamimura, Ryuichiro; Osada, Yamato; Takagi, Hideki; Hirayama, Hideki
• Is Part Of: Applied physics express. Volume 11:Number 1(2018)
• Publication Date: 2017-11-30
• Subjects: Physics -- Periodicals; Technology -- Periodicals; 621.05
• DOI: 10.7567/APEX.11.012101
• Languages: English
• ISSNs: 1882-0778

Abstract

Abstract: We increased the light-extraction efficiency (LEE) of AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) by introducing a highly reflective photonic crystal (HR-PhC) into the surface of the p-AlGaN contact layer, thereby achieving a high external quantum efficiency (EQE). A low-damage HR-PhC with a lattice period of approximately 250 nm was fabricated using nanoimprinting and dry etching. A reflective Ni/Mg p-type electrode was deposited on the HR-PhC layer using a tilted-evaporation method. The EQE of a conventional DUV LED with emission around 283 nm was increased from 4.8 to 10% by introducing the HR-PhC and the reflective Ni/Mg electrode. A simple estimation of the effective reflectance of the HR-PhC p-AlGaN contact layer with the Ni/Mg electrode indicated a value exceeding 90%.