Anion-Cation Site Dependence of Pressure Coefficients for Donors in GaAs

The theoretical model, based on the many-band approach, is proposed for the strongly localized donor states in GaAs. The pressure coefficients for the states of A$\text{}_{1}$ and Τ-2 symmetry have been calculated for the donors at the anion and cation sites. The obtained results show that these pressure coefficients are different from the conduction-band pressure coefficients and are dependent on the lattice site occupied by the impurity as well as on the symmetry of the donor states.