Surface morphology on high-temperature plasma-etched gallium nitride

Abstract

We report the surface morphology of gallium nitride (GaN) films during the argon and nitrogen plasma etching at elevated temperatures up to 800°C. For Ar plasma at high substrate temperatures above 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. In N₂ plasma exposure, the N/Ga remains stoichiometric with higher values above 0.85, and the surface is not significantly roughened, even higher at 600°C. Therefore, the aggregation of metallic Ga induces surface roughening during ion-enhanced etching of GaN with elevated substrate temperatures.