A High-Temperature Nitrogen Plasma Etching for Preserving Smooth and Stoichiometric GaN Surface

We report the damageless surface morphology of gallium nitride (GaN) films during argon and nitrogen plasma etching at elevated temperatures up to 600 °C. For Ar plasma bombardment at high substrate temperatures of around 600 °C, Ar+ ion bombardment dissociates Ga–N bonds by the preferential removal of nitrogen, which promotes roughness of the GaN surface by the aggregation of gallium atoms. For the N2 plasma one, the N/Ga remains stoichiometric with higher values above 0.69, and the surface is not significantly roughened, even at 600 °C. Therefore, the aggregation of metallic Ga induces surface roughening during ion-enhanced etching of GaN at elevated substrate temperatures.