Preparation of Experiments on the Growth of Cadmium-Zinc Telluride Crystals under Microgravity Conditions

Cd_{1 – x}Zn_xTe crystals are required for ionizing radiation detectors, which are widely used in science, technology, medicine, and other fields. Grown-in dislocations arise and low-angle boundaries form during crystal growth due to strains caused by crystallization. A typical problem of Cd–Zn–Te ternary compounds grown from melt are tellurium inclusions, which worsen the efficiency of detector operation. Microgravity conditions provide unique opportunities for the growth of high-quality crystals on account of the lack of convection, more equilibrium mixing of the melt, and a decrease in internal stresses. Since the properties of such crystals greatly depend on the production conditions, a seed and a feed ingot are needed with predetermined composition and structure. Ampoules with two compositions of the material have been prepared for space experiments. The crystals have been grown from loads with the compositions Cd_0.96Zn_0.04Te and Cd_0.9Zn_0.1Te, each consisting of an oriented seed, a solvent, and a feeding ingot. The latter are single-phase single crystals, with a chosen orientation and low dislocation density, which comply with the requirements for the growth of CZT crystals under microgravity conditions. The ampoules with the materials have been sent to the International Space Station (ISS) for CZT crystal growth using equipment for growth already installed on board the “Nauka” module.