Excitonic recombination processes in GaAs grown by close-space vapour transport

Epitaxial GaAs layers were grown using the close-space vapour transport. From deep level transient spectroscopy measurements, the native EL2 donor has been observed in all of the layers with deposition temperature-dependent concentration. On the GaAs samples, also performed are photoluminescence experiments in the temperature range 10–300 K. Two peculiar features were revealed: (i) the radiative recombination in GaAs layers is increasingly dominated by bound–exciton transitions, (ii) the excitonic luminescence is found to be very sensitive to the growth conditions. A study of the near-band-edge photoluminescence as a function of power excitation and temperature has been done in an attempt to elucidate the origin of the enhanced bound–exciton luminescence. q 2004 Elsevier Ltd. All rights reserved.