The optical properties of n-type material which was grown by hydride vapor-phase epitaxy, with intentional Si-doping levels ranging up to 4 x 1017/cm3, were investigated by means of low-temperature photoluminescence techniques. Free and neutral donor-bound exciton transitions and 2-electron satellites were identified at 1.7K. The energy difference between the principal neutral donor-bound exciton peak and its 2-electron satellites yielded a Si donor binding energy of 0.022eV. The intensity of the Si-related 2-electron satellites increased with increasing Si concentration. The Si donor was much shallower than the 2 residual donors, which had binding energies of 0.028 and 0.034eV. This suggested that the main residual donors were not Si. The Si doping also introduced an acceptor level with a binding energy of about 0.224eV.

Optical Spectroscopy of Si-Related Donor and Acceptor Levels in Si-Doped GaN Grown by Hydride Vapor Phase Epitaxy. J.Jayapalan, B.J.Skromme, R.P.Vaudo, V.M.Phanse: Applied Physics Letters, 1998, 73[9], 1188-90