Photoluminescence and X-ray photoelectron spectroscopy measurements were used to study the effects of (NH4)2Sx treatment on p-type GaN. After the (NH4)2Sx treatment, it was found that a reduction in the surface state, related to N-vacancy defects on the p-GaN surface, led to an 0.25eV reduction in surface band-bending. The intensity of the 2.8eV photoluminescence band depended upon the number of N vacancies.

Surface Band Bending, Nitrogen-Vacancy-Related Defects and 2.8eV Photoluminescence Band of (NH4)2Sx-Treated p-GaN. Y.J.Lin, Z.L.Wang, H.C.Chang: Applied Physics Letters, 2002, 81[27], 5183-5