Ampoule Carbon Coating and Defects in CdMnTe Crystals intended for Applications in Nuclear Radiation Detection

Cadmium manganese telluride (CdMnTe) has a high potential for applications in room-temperature X-ray and gamma-ray detection due to its high average atomic number (48 for Cd, 25 for Mn, and 52 for Te) that is essential to having high stopping power for incident high-energy electromagnetic radiations. A major obstacle in developing CdMnTe detectors is growing crystals free of defects, such as Te inclusions, sub-grain boundary networks, and precipitates. Herein, we present our preliminary results of growing CdMnTe crystals by the Bridgman method; the experiments were aimed at studying the effects of growth parameters, such as ampoule shape, size, and carbon coating thickness on defects in the ingot. Our goal was to optimize growth parameters so to reduce/eliminate growth related defects. With a carbon coating of about 2 mu m, created by cracking spectroscopic-grade acetone at similar to 900 degrees C, we observed very few grain boundaries and grain-boundary networks.