Study of etching‐induced damage in GaN by hard X‐ray photoelectron spectroscopy

We carried out nondestructive measurements of the depth profile of etching‐induced damage in p‐type gallium nitride (p‐GaN), in particular surface band bending, using Hard X‐ray Photoelectron Spectroscopy (HAX‐PES). HAX‐PES at different take‐off angles of photoelectrons made it clear that etching by inductively coupled plasma (ICP) introduced donor‐like states in a surface layer of GaN. We were able to quantitatively analyze band bending and charge distribution in an etched p‐GaN. The analysis results indicated the existence of deep donors with a concentration of 1–2 × 1020 cm−3 in a surface layer whose thickness increased with increasing a bias power of ICP.