Deep donor levels in semiconductors with vacancies in the anion sublattice
The impurity energy spectrum of undoped bulk n-types: GaAs, InAs, CdSnAs<sub>2</sub>, CdTe, and ZnO, has been investigated, being based on the quantitative analysis of baric and temperature dependences of kinetic coefficients. The deep donor center in these semiconductors is found to be corresponded to an intrinsic defect of vacancy in the anion sublattice. We have determined: 1) positions of the energy levels against the conduction band bottom for each listed specimen and 2) the pressure coefficients for these levels. The shifts of the deep donor levels towards the depth of conduction band have been calculated as the function of a band gap width, manifesting their resonant-type nature for InAs and CdSnAs<sub>2</sub>. The dependences of Hall coefficient and specific resistance in n-InAs and n-CdSnAs<sub>2</sub> are similar, due to the presence of a deep donor center whose energy level is on the continuous spectrum of the conduction band in both compounds, and the difference in the pressure at which these dependences are sharply enhanced, due to the fact that the initial electron concentrations in the samples studied differ by two orders of magnitude. In bulk n-GaAs crystals with a concentration of excess donors, the presence of a deep donor level was found from the temperature dependences of specific resistance and Hall coefficient at atmospheric pressure. A quantitative analysis of such a strong dependence of specific resistance on undoped n-CdGeAs<sub>2</sub>, analogous to the quantitative analysis done in n-CdSnAs2, agrees with the presence of the energy level of the deep donor center of the arsenic vacancy on the brink of the conduction band.