POLARIZATION PHOTOLUMINESCENCE STUDY OF THE COMPLEX VGATEAS IN N-TYPEGAAS IN THE TEMPERATURE-RANGE 77-230 K

The polarization of the photoluminescence band with a maximum near 1.1 8 eV, which is formed as a result of the resonance excitation of VGaTe As complexes by polarized light, is investigated for GaAs:Te with vari ous electron densities irm the temperature range 77-230 K. Based on a previously developed model of these defects, theoretical equations for the polarization of their luminescence are derived in the one-dipole approximation, taking into account the possible reorientation of Jahn- Teller distortions of the complexes. It is shown that the temperature dependence of the polarization of the investigated band is well descri bed by these equations, and the: parameters characterizing the optical dipoles of the complexes are estimated. A decrease in the degree of p olarization at temperatures above similar to 120 K is explained by the transfer of excitation to complexes with any possible orientations of the initial axis and by Jahn-Teller distortion (owing to thermal-fiel d emission and retrapping of holes by the photoexcited complexes). The decrease in polarization can also be partially linked to the reorient ation of distortions during the lifetime of the emitting state of the complex. The height of the energy barrier for such reorientation is at least similar to 200 meV. (C) 1997 American Institute of Physics.