Synchrotron-based core level photo-emission measurements and near-edge X-ray absorption fine structure spectroscopy were used to identify and characterize N interstitials in p-type GaN, created by N bombardment. From absorption measurements around the N K-edge N interstitial levels within the band gap were identified; in good agreement with theoretical predictions. The reduction in band bending determined from photoemission measurements was explained by the acceptor-like character of these defects. Argon bombardment produces N vacancies and the metallic Ga phase at the surface, which will produce the increased band bending and pinning of the surface Fermi level closer to the conduction band minimum.

Defect Acceptor and Donor in Ion-Bombarded GaN. M.Petravic, V.A.Coleman, K.J.Kim, B.Kim, G.Li: Journal of Vacuum Science & Technology A, 2005, 23[5], 1340-5