CdZnTe

CdZnTe, or CZT, is a ternary II-VI semiconductor alloy of cadmium telluride and zinc telluride with the chemical formula Cd1−xZnxTe, where 0 ≤ x ≤ 1. It is used in devices that benefit from a wide, tunable bandgap and high atomic numbers.

CdZnTe crystallizes in the zinc blende (sphalerite) structure, the same as CdTe and ZnTe. By varying the zinc content, the bandgap can be tuned from values near CdTe up to ZnTe, roughly spanning about 1.5–2.2 eV at room temperature. This tunability, combined with a direct bandgap, enables devices with relatively low intrinsic carrier concentration that can operate without cryogenic cooling.

The material possesses high average atomic numbers (Cd, Zn, Te), providing strong gamma-ray and X-ray stopping power. Its wide bandgap supports operation at or near room temperature, making CZT attractive for radiation detector applications. Achieving high resistivity (on the order of 10^9–10^11 ohm·cm) requires careful compensation of native defects, and devices are often doped to tailor conduction type and carrier transport properties.

Growth and processing of CdZnTe are technically challenging. Commercial and research-grade crystals are commonly grown by methods such as the Bridgman technique or the Traveling Heater Method, with horizontal or vertical gradient freezing variants. Common defects include tellurium inclusions, cadmium vacancies, and dislocations, which can affect detector performance. Post-growth processing, surface treatment, and careful environmental controls are used to improve crystal quality.

Applications center on radiation detection, including room-temperature X-ray and gamma-ray detectors for medical imaging, homeland security, industrial nondestructive testing, and spectroscopy. While CZT offers advantages in mobility and resolution, production cost and defect control remain important factors.