Electrical Transport and Photoelectronic Properties of ZnTe:Al Crystals

Abstract

A study of native and impurity defect levels in Al-doped high-resistivity ZnTe is described. Experimental information includes electrical transport, photoluminescence, and photoconductivity measurements. Analysis of this information led to the following defect-level assignments: an acceptor level 0.25 eV from the valence band, attributed to a Zn-vacancy-Al-donor complex; an acceptor level 0.60–0.65 eV from the valence band, assigned to a native defect, possibly the second level of a zinc vacancy; and a donor level 0.1 eV from the conduction band, assigned to the dopant aluminum. These levels are involved in radiative recombination which gives rise to three photoluminescence bands with peaks near 2.11, 2.04, and 1.63 eV at 77 °K, observed in Zn-vapor-annealed ZnTe : Al single crystals.