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Diffusion lengths of minority carriers in single crystals produced by the vertical gradient freezing method were studied. Au evaporated area was used as a Schottky barrier. Electron beam induced current images in the scanning electron microscope were used for an evaluation of minority carrier diffusion lengths at 300 K in different samples.

The works concerning the data regarding solid-phase transformations in cadmium telluride are considered. On the basis of these works the region of CdTe homogeneity has been plotted. The region is characterized by Cd and Te solubility in the range of 1019–1020 cm−3 as well as availability of two-phase fields in the temperature range of solid-phase transformations. This analysis and some technological investigations resulted in conclusions about the substantial influence of composition and post-crystallization cooling of crystal on its microstructure, optical and electrical properties. These conclusions are related to high-temperature synthesis of crystals, for example, in the application of the Bridgman method.

Cd 1-x Zn x Te (x = 0.04-0.1) single crystals with a diameter up to 100 mm and maximum height of 35 mm were prepared in a vertical arrangement by gradual cooling of the melt. The crystals grew in most cases in (1 1 1) orientation and they are twin-free. The average density of dislocation pits is 5 x 10 4 cm -2 . The FWHM values ranging from 25 to 8 arcsec were obtained on the (1 1 1 )A face even near the edge of the ingot. Optical transmittance reaches 63% at 10 μm in most cases. The typical single crystals are p-type with a carrier concentration in the range of 10 14 -10 16 cm -3 and mobility of 50-100 cm 2 /V s at 300 K. An important acceptor level influencing carrier concentration was found to be 140 meV above the valence band. Diffusion length of both minority electrons and holes was determined to be typically 3-10 μm. In the luminescence spectra, free and bound exciton recombination bands were resolved together with donor-and acceptor- type defect features.