Photoluminescence of high-resistivity ZnTe crystals doped with gallium and indium

We have measured photoluminescence spectra of high-resistivity ZnTe crystals doped with gallium and indium in the wide energy range from near-band-edge energy to deep energy region up to 0.78 eV. In the near-band-edge energy, we detected a characteristic excitonic peak at 2.363 eV in both gallium and indium doped high resistivity ZnTe. By comparison with a similar PL peak observed in high resistivity CdTe, we identified the characteristic peak at 2.363 eV as emission from excitons bound to defects complex arising from a Zn vacancy and gallium or indium atoms (VZn-2D). In lower energy range, a newly strong deep emission band near 1.0 eV has been observed for the first time in high-resistivity ZnTe crystals. The intensity of the deep emission is two order magnitude stronger than that in undoped one. Furthermore, the intensity and peak position of the deep emission band are almost unchanged by Zn-saturated anneal at 600-680 °C. We specualte that this deep emission band is responsible for the high resistivity of ZnTe and prevent conversion of n-type low resistivity. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)