InGaN-based light-emitting diodes with an embedded conical air-voids structure.
The conical air-void structure of an InGaN light-emitting diode (LEDs) was formed at the GaN/sapphire interface to increase the light extraction efficiency. The fabrication process of the conical air-void structure consisted of a dry process and a crystallographic wet etching process on an undoped GaN layer, followed by a re-growth process for the InGaN LED structure. A higher light output power (1.54 times) and a small divergent angle (120°) were observed, at a 20 mA operation current, on the treated LED structure when compared to a standard LED without the conical air-void structure. In this electroluminescence spectrum, the emission intensity and the peak wavelength varied periodically by corresponding to the conical air-void patterns that were measured through a 100 nm-optical-aperture fiber probe. The conical air-void structure reduced the compressed strain at the GaN/sapphire interface by inducing the wavelength blueshift phenomenon and the higher internal quantum efficiency of the photoluminescence spectra for the treated LED structure.
Department of Materials Science and Engineering, National Chung Hsing University,Taichung 402, Taiwan.
Yu-Chieh
YC
Huang
Chia-Feng
CF
Lin
Sy-Hann
SH
Chen
Jing-Jie
JJ
Dai
Guei-Miao
GM
Wang
Kun-Pin
KP
Huang
Kuei-Ting
KT
Chen
Yi-Hsiang
YH
Hsu