Low noise gamma-ray and X-ray detectors based on CdTe-materials

In this work, charge collection and noise properties of cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detectors are studied and compared. It is shown how charge collection efficiency affects the noise properties of detectors. The low mobility—lifetime products of the charge carriers limit the noise properties, the charge collection efficiency, and timing properties in CdTe detectors. By using the high pressure Bridgeman (HPB) method to grow Cd1 − xZnxTe (CZT), better stability, reliability and lifetime are achieved. The introduction of ZnTe increases the bandgap of the crystal, thereby reducing the leakage current in the detectors. Further, the noise due to charge trapping appears to be much less in the CZT detectors, which are also very stable. Hence, one of the major complaints against the CdTe based detector technology has been removed.