Photoenhanced wet etching of n-gallium nitride

Photoassisted electrochemical (PEC) etching of n-doped GaN layer grown on sapphire in a KOH based solution under illumination of a Hg arc lamp is demonstrated. Smooth surfaces were obtained for a narrow range of etching conditions. It was found that this window could be extended by using etch conditions which produced "whiskers". Subsequent post treatment in developer AZ 400 K and KOH solution was used to remove these whiskers. An influence of the surface treatment of GaN by wet chemical etching prior to the Schottky barrier metal deposition was investigated.