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Among semiconductor materials with wide band gap, much attention has been paid to CdTe and Cd 1-x Zn x Te as roomtemperature detectors of X-ray and gamma-radiation. They have high atomic number (~ 50), high density (> 6 g/cm 3) and relatively high carrier mobility. It has been shown that formation of solid solutions CdTe-ZnTe is accompanied by broadening of the band gap, increase of resistivity (by more than an order of magnitude), and improved stability of spectral characteristics as compared with CdTe [1]. A general problem for semiconductor materials based on A II B VI compounds is the difficulty of growing structurally perfect crystals characterized by high degree of chemical purity and stoichiometry. Requirements to the structural perfectness of crystals Cd 1-x Zn x Te are very high, because practically all their principal electrophysical and optical characteristics are strongly structure-dependent. The present work was focussed on studying effects of preparation conditions of crystals Cd 1-x Zn x Te upon concentration of electrically active structural defects in this material and X-ray sensitivity of detectors made on its base. 2. Experimental procedure We studied a set of crystals Cd 1-x Zn x Te (32 mm in diameter) grown by Bridgman method in vertical compression furnaces under inert gas (argon) pressure from 3.5 to 5.5 MPa. Crystal growth regimes are presented in Table 1. In this work, crystals Cd 1-x Zn x Te were grown using raw materials pre-synthesized in a quartz ampoule, as well as those synthesized from elements (Cd,Zn,Te) directly in the growth equipment. During growth of certain crystals (No. 9-12) gas samples were taken to analyze concentration of oxygen-containing impurities in the atmosphere of the growth furnace. Carbon oxide content at different growth stages varied from 0.1 to 3 vol. %. Concentration of oxygen and water vapor in the initial argon did not exceed 1⋅10-3 vol. %. It could be concluded that in the growth furnace carbon oxide was formed from the air desorbed from the construction material, and its removal was necessary. Quality and uniformity of the properties and structure of the grown crystals was determined by several independent

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