Improved a-plane GaN quality grown with flow modulation epitaxy and epitaxial lateral overgrowth on r-plane sapphire substrate
Journal
Applied Physics Letters
Journal Volume
92
Journal Issue
23
Date Issued
2008
Author(s)
Huang, Jeng-Jie
Shen, Kun-Ching
Shiao, Wen-Yu
Chen, Yung-Sheng
Liu, Tzu-Chi
Tang, Tsung-Yi
Huang, Chi-Feng
Abstract
The authors demonstrate superior crystal quality of a-plane GaN grown on r-plane sapphire substrate based on the flow modulation epitaxy (FME) technique, in which the Ga atom supply is alternatively switched on and off with continuous nitrogen supply. With the FME technique, a high growth rate of 2.3μm∕h can still be achieved. With or without epitaxial lateral overgrowth (ELOG), either c- or m-mosaic condition is significantly improved in the samples of using FME. With ELOG, the surface roughness can be reduced from 1.58to0.647nm in an area of 10×10μm2 microns by using the FME technique. Based on the results of photoluminescence measurement, one can also conclude the better optical property of the FME-grown a-plane GaN thin films. Besides, it is shown that tensile strain is more relaxed in the FME samples.
Type
journal article