INVESTIGATION OF THE VGASNGA COMPLEX IN GAAS BY THE POLARIZATION PHOTOLUMINESCENCE AND PIEZOSPECTROSCOPIC METHODS .2. PHENOMENON OF 2-STAGEALIGNMENT

A two-stage pressure dependence of the polarization of the photolumine scence emitted by V(Ga)Sn(Ga) complexes in GaAs, observed at 2 K under uniaxial pressures applied along the [111] or [110] axes, is explaine d as follows: At a certain pressure exceeding the critical value an ad ditional alignment appears in a group of V(Ga)Sn(Ga) complexes with a certain orientation of the initial V(Ga)-Sn(Ga) axis relative to the d irection of the applied pressure. This alignment occurs as a result of suppression, by an external uniaxial strain, of the perturbation of t he state of a Ga vacancy caused by an atom of Sn located at a Ga subla ttice site closest to V(Ga). Possible reasons for the absence of two-s tage alignment in V(Ga)Te(As) complexes are considered.