PHOTOACOUSTIC INVESTIGATION OF THE CARRIER TRANSPORT PROCESSES AND THE THERMAL-PROPERTIES IN N-TYPE GAAS

The carrier-transport processes and the thermal properties of n-type G aAs were investigated by using photoacoustic spectroscopy. The frequen cy dependence of the photoacoustic signal showed that the photoacousti c effects in n-type GaAs were associated with instantaneous thermaliza tion, nonradiative bulk recombination, and nonradiative surface recomb ination. In particular, it was found that in the high-frequency region the heat was primarily generated by the nonradiative bulk recombinati on and the nonradiative surface recombination processes. For the low-f requency region, however, the instantaneous thermalization process was the main origin of the heat. A thermal diffusivity of 0.51 cm(2)/s, a diffusion coefficient of 5.2 cm(2)/s, a surface recombination velocit y of 355 cm/s, and a relaxation time of 5.8 mu s were also obtained fr om the curve fitting of the photoacoustic phase spectrum.