Preparation of Experiments on Growing Zinc–Cadmium Telluride Crystals in Microgravity

Abstract

Cd1-xZnxTe crystals are necessary for the production of ionizing radiation detectors widely used in science, technology, medicine and other fields. Internal stresses during crystallization lead to generation of dislocations and low-angle boundaries. Typical problem of melt crystal growth of Cd-Zn-Te compounds are tellurium inclusions, which deteriorate detector performance. Microgravity conditions provide unique opportunities for growing high-quality crystals due to the absence of convection, more equilibrium conditions of melt mixing, and a decrease in internal stresses. Since the properties of such crystals strongly depend on the production conditions, seeds and a feed ingot with specified compositions and structure are required. Ampoules with two compositions of materials have been prepared for the space experiment. Crystals of different compositions Cd0.96Zn0.04Te and Cd0.9Zn0.1Te were produced for two charges. They consist of an oriented seed, solvent, and feeding ingot, which are single-phased, single crystalline, have certain crystallographic orientation, meet demands for growth of Cd–Zn–Te crystals in microgravity. Ampoules containing these materials were sent to International Space Station for crystal growth on equipment already assembled at “Nauka” station.