Optical characteristics of 1.18-eV luminescence band complexes in n-GaAs:Sn(Si): Results of a photoluminescence study with polarized resonant excitation

Abstract

Experimental values of the polarization of the low-temperature luminescence from the V _GaSn_Ga and V _GaSi_Ga complexes in n-GaAs under conditions of resonant excitation by polarized light propagating along the [110] or [100] crystal axis are compared with expressions obtained in the classical dipole approximation for defects with triclinic or monoclinic symmetry. It is shown that the rotator fraction in the superposition of rotator and oscillator contributions to the emission of the complexes is 17–18%. The direction of the axis of these dipoles, which matches the experimental data, is consistent with the assumption that the effect of the donor on the vacancy orbitals of a hole localized in the complex is lower than that of the Jahn-Teller effect. The resulting symmetry of the complex may be monoclinic or triclinic. In either case, deviation of the optical dipole axis of the complex from the dipole axis of an isolated V _Ga vacancy distorted as a result of the Jahn-Teller effect is lower for the V _GaSn_Ga and V _GaSi_Ga complexes than for V _GaTe_As complexes. This means that the effect of the donor on the electron structure of the V _GaTe_As complexes is greater than in the V _GaSn_Ga and V _GaSi_Ga complexes. This correlates with the difference in the donor position in these complexes.