Basic principles of postgrowth annealing of CdTe:Cl ingot to obtain semi-insulating crystals

The process of annealing of a CdTe:Cl ingot during its cooling after growth was studied. The annealing was performed in two stages: a high-temperature stage, with an approximate equality of chlorine and cadmium vacancy concentrations established at the thermodynamic equilibrium between the crystal and vapors of volatile components, and a low-temperature stage, with charged defects interacting to form neutral associations. The chlorine concentrations necessary to obtain semi-insulating crystals were determined for various ingot cooling rates in the high temperature stage. The dependence of the chlorine concentration [Cl-Te(+)] in the ingot on the temperature of annealing in the high-temperature stage was found. The carrier lifetimes and drift mobilities were obtained in relation to the temperature and cadmium vapor pressure in the postgrowth annealing of the ingot. (C) 2000 MAIK "Nauka/Interperiodica".