Photoenhanced wet chemical etching of n+-doped GaN

Photoelectrochemical etching (PEC) was applied to pattern n-doped gallium nitride surfaces on micrometer and submicrometer scales using potassium hydroxide (KOH) solution. We have tested conditions that lead to a smooth surface after etching for features with dimension of 0.5–10 μm. Dependence of the etched surface quality on etchant concentration was observed. Conditions for relatively smooth final etched surfaces were applied to etch gratings in submicrometer ranges. Anisotropic etching in a hot KOH solution is used to smooth the PEC-etched surface. Comprehensive evaluation of the resulting profiles and surface roughness by SEM is presented and discussed.