Evolution of Bottom c-Plane on Wet-Etched Patterned Sapphire Substrate

Wet-etched pattern sapphire substrate (PSS) has been employed to improve the epitaxy of GaN-based LEDs. It was found that the crystal quality and performance of LEDs improved with decrease in c-plane areas of PSS. However, further decrease in bottom c-plane areas makes epitaxy of GaN film very difficult. In this research, the evolution of bottom c-plane was investigated through a systematic study. It was found that epitaxy difficulty might be due to the appearance of 6C facets {4 (1) over bar(3) over bar 18} and the disappearance of bottom c-plane. (C) 2013 The Electrochemical Society.