Single crystals were prepared by means of the cold travelling heater method and were investigated by using photoluminescence and cathodoluminescence techniques. The spectral range which was investigated extended into the near-infrared (below 2μ), where several emission bands with maxima between 0.79 and 1eV were detected. A large contribution of deep-level bands to the luminescence spectrum was noted. Differing kinetic behaviors, as a function of temperature, were reported for the various components. Differences were found between the spatial distribution of the centres that were involved in infra-red emissions and those associated which were associated with transitions in the visible range.The spatial distribution of the cathodoluminescence emissions suggested that these bands were related the presence of extended defects such as dislocations.

P.Fernández, J.A.García, A.Remón, J.Piqueras, V.Muñoz, R.Triboulet: Semiconductor Science and Technology, 1998, 13[4], 410-6