Etching damages on AlGaN, GaN and InGaN caused by hybrid inductively coupled plasma etch and photoenhanced chemical wet etch by Schottky contact characterizations

The surface damaging effects of the inductively coupled plasma (ICP) etch and the photoenhanced chemical (PEC) wet etch on AlGaN, GaN and InGaN were systematically investigated. The surface morphologies and the etch rates after ICP etch and PEC wet etch were explored to achieve optimum conditions for a hybrid etch technique. The etch rates increased with the ICP power or concentration of KOH(aq) and the surface roughness was less after PEC wet etch than it was after ICP etch. Schottky characterizations of GaN and AlGaN diodes after pure ICP etch, pure PEC etch and hybrid ICP/PEC etch were investigated to elucidate the damaging effects on the surfaces. It shows that the PEC etch is an effective way to achieve a damage-free surface for GaN-based materials, and the hybrid ICP/PEC etch can be used for applications which require high etch rate and damage-free surfaces.