Two differing trends of plasma damage in n-type GaN were observed. The 2 modes of etching characteristics were attributed to the presence of Ga vacancies in the material. The resistivity of GaN with Ga vacancies increased upon plasma exposure through electrical compensation by the formation of deep acceptor states as a result of vacancy-complex formation. GaN samples free of Ga vacancies showed a reduction of resistivity as N vacancies were produced through interactions with the plasma. These results correlate well with the photoluminescence spectra, where a significant yellow-band emission was detected from the samples with a high concentration of Ga vacancies.

The Link between Gallium Vacancies and Plasma Damage to n-Type GaN. H.W.Choi, S.J.Chua: Physica Status Solidi A, 2001, 188[1], 393-7