Sharp photoluminescence lines were detected in semi-insulating material which had been diffused with low Li concentrations. These lines were presumed to be identical to the weak lines which had previously been obtained merely by heat treatment, although their relationship to photoluminescence bands at 1.34 and 1.45eV seemed to be uncertain. A new line at 1.466eV was attributed to an exciton that was bound to a neutral electrically inactive deep defect which involved Li. Lines at 1.508 and 1.510eV were attributed to excitons that were bound to acceptors, while a new broad peak at around 1.501eV was suggested to arise from a donor-to-acceptor transition to a shallower acceptor than had previously been observed in GaAs. It was concluded that the lines in question were most likely to originate from native acceptor complexes, such as VGa-GaAs pairs which were created by Li diffusion. In this case, the activation energy for the formation of these complexes was strongly reduced by the presence of Li. A third line, at 1.466eV, was attributed to an exciton that was bound to a neutral complex that involved Li.

H.P.Gislason, B.H.Yang: Materials Science Forum, 1995, 196-201, 201-6