Photoenhanced wet etching of gallium nitride in KOH-based solutions

Photoelectrochemical etching (PEC) of n(+)-GaN in KOH and AZ400K photoresis t developer is presented. We compare the two solutions used for PEC etching without an external bias. The influence of etchant concentration and of th e intensity of ultraviolet illumination was studied with emphasis on the re sulting etched surface quality. The quality of the shallow etched surface a nd its roughness are presented. The AZ400K etchant was applied to shallow e tching of n(+)-GaN with threading dislocation densities in the range of 10( 9)-10(10) cm(-2). Moreover, the first analysis of photocurrent monitoring d uring the electrochemical etching of GaN epitaxial layers in KOH is present ed. We found that photocurrent very sensitively reflected the changes in th e quality of the etched surface. (C) 2001 American Vacuum Society.