Direct experimental evidence for the role of oxygen in the luminescent properties of GaN

We present experimental evidence of electron-beam-induced diffusion of O an d H in unintentionally doped n-type GaN grown on a sapphire substrate. Impu rity diffusion was investigated using cathodoluminescence kinetics and imag ing at 4 and 300 K and by wavelength dispersive x-ray analysis. The results illustrate the significance of electron-beam-induced electromigration in w ide band gap semiconductors, confirm the roles of O-N(.) in bound exciton, donor-acceptor pair and yellow emissions and suggest the involvement of O-N (.) and hydrogenated gallium vacancies in the previously unexplained blue l uminescence. [S0163-1829(99)09403-5].