It was noted that photoluminescence bands, at 0.778 and 0.85eV, were greatly enhanced by the low-temperature heat treatment of plastically deformed material. The H passivation of samples resulted in a reversible distribution of the photoluminescence spectrum, which was attributed to the passivation of defect levels that were created during heat treatment. The temperature and doping dependences of the emissions suggested that the new emissions originated from electronic transitions between defect levels, in the upper half of the energy gap, and dislocation-related energy levels. A tentative model for pair recombination between O-related donors and dislocation acceptors was tested. By using this model, and comparing predicted and measured spectra, the energy position of the D1 dislocation acceptor was found to be situated at about 0.36eV above the valence band.

E.A.Steinman, H.G.Grimmeiss: Semiconductor Science and Technology, 1998, 13[1], 124-9