Abstract:
The results of studies of $\mathrm{Ga}$ vacancy $({V_\mathrm{Ga}})$ – shallow donor ($\mathrm{Te}$ or $\mathrm{S}$ atom substituting $\mathrm{As}$ atom in the lattice site closest to the vacancy) complexes by methods of photoluminescence under resonant polarized excitation and piezospectroscopy are considered. An analysis of the experimental data in the classical dipole approximation shows that the symmetry of the complexes is lower than the trigonal one and their optical properties are explained in the model of a monoclinic defect with a symmetry plane of the $\{$011$\}$ type, in which the initial trigonal axis and the axis of the optical dipole lie. The reason for the lowering of the symmetry of the initially trigonal center is the distortions arising from the Jahn–Teller effect. A microscopic model is proposed that relates the behavior peculiarities of the optical properties of the $V_{\mathrm{Ga}}\mathrm{Te}_{\mathrm{As}}$ complex under uniaxial deformations and temperature changes with the structure of the electronic levels and the change in the charge state of the complex. The differences in this behavior observed for the $V_{\mathrm{Ga}}\mathrm{S}_{\mathrm{As}}$ complex are analyzed and possible reasons for their appearance are discussed.
Keywords:vacancy complexes in $\mathrm{GaAs}$, Jahn–Teller effect, photoluminescence under resonant excitation, piezospectroscopy.
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