UV-photoassisted etching of GaN in KOH

The etch rate of GaN under ultraviolet-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias, and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n similar to 3 x 10(16) cm(-3)) GaN are greater than or equal to 1000 Angstrom.min(-1). The etching is diffusion-limited under our conditions with an activation energy of similar to 0.8kCal.mol(-1). The etched surfaces are rough, but retain their stoichiometry.