added Ar plasma at high substrate temperature

Atomic layer etching (ALE) of Gallium nitride (GaN) by cyclic exposure of BCl₃ gas and F₂ added Ar plasma was demonstrated at high substrate temperature. The etching was promoted even at a low ion energy of 23 eV at substrate temperatures over 200°C and the rate was self-limited within a mono layer. The etching damage evaluated by photoluminescence (PL) was mitigated by increasing the substrate temperature. From the evaluation of composed atoms on etched surface by XPS, the damage mitigation was attributed to reduction of remained halogens on etched surface.