Photoluminescence of CdTe grown in conditions considerably deviating from thermodynamic equilibrium

Abstract

Undoped cadmium telluride produced in different conditions of fast crystallization of the vapor phase at temperatures of 420–600°C is studied by the low-temperature photoluminescence technique and electrical measurements. It is shown that, despite the relatively high rate of growth (∼1 μm s−1), the basic parameters of the lattice and band structure of the material are close to the corresponding parameters reported in publications for single-crystal CdTe. The conductivity type of the crystals grown in the study is controlled by hydrogen-like donors and acceptors associated with background impurities. It is found that, along with background impurities in n-type textures, there exist compensating acceptors with the nonstandard activation energies 48.5 ± 0.5, 98.0 ± 0.5, and 119.5 ± 0.5 meV. It is shown that the lowered temperature of growth, together with the excess tellurium content, yields a sharp increase in the concentration of deep electron states and isoelectronic defects with lowered symmetry.