Films of Si-doped material were grown onto c-plane sapphire substrates by means of molecular beam epitaxy, using a N radio-frequency plasma source. Thermal annealing was performed under a N atmosphere, and double-crystal X-ray diffraction and 77K photoluminescence techniques were used to investigate the effects of annealing using various temperatures and times. The double-crystal X-ray diffraction data showed that the dislocation density decreased during annealing. The 77K photoluminescence, of samples which were annealed for longer than 300s at 950C, exhibited a new peak at 378nm. The integrated intensity of the peak increased markedly with increasing annealing time. The excitation power-dependence of the 378nm peak indicated that the emission was associated with donor-acceptor pair transitions, and a similar peak was observed in highly Si-doped material. The acceptor in donor-acceptor pairs was suggested to be SiN.

Post-Growth Thermal Annealing of GaN Grown by RF Plasma MBE. W.Li, A.Li: Journal of Crystal Growth, 2001, 227-228, 415-9