Photoetching Mechanisms of GaN in Alkaline S[sub 2]O[sub 8][sup 2−] Solution

A study of the electrochemistry of n-type GaN in an alkaline peroxydisulfate solution was used to explain the mechanism of photoetching of the semiconductor under open-circuit conditions. The observed enhancement of the photoetch rate as a result of platinum either directly on or in electrical contact with the semiconductor is shown to be mainly a photogalvanic effect. The factors determining the etching kinetics and surface morphology are elucidated.