NbN Capping Layer for Enhanced Thermal Processing of Group III-Nitride Semiconductor Devices

Annealing of GaN and GaN based ternaries at high temperatures requires a capping layer, which can withstand applied temperatures and protect the surface of the III-nitride material from decomposition. AlN cap is often used as this capping layer, but it is very resistant to wet etching and requires harsh chemical, largely KOH-based etchants, for removal. In this work NbN was used as a new material for high temperature capable cap that is easily removable using wet processing. It was shown that NbN is capable of avoiding decomposition when used on an InGaN layer that is subjected to annealing temperatures up to 1220°C. In addition, it was demonstrated that the NbN capping layer can be completely removed using a HF/HNO3wet process.