Improved CZT Detectors by Unique Surface Treatments and Innovative Contacts

CZT (Cd0.9Zn0.1Te) gamma radiation detectors are presently the best candidates for room temperature operation, in order to identify radiological isotopes in materials for military, medical, and commercial applications. Presently, the typical energy resolution of CZT detectors is on the order of 2%, rather than the desired =5%. To achieve this energy resolution goal, this project will employ novel contact fabrication techniques, unique post growth treatment, and surface modifications. The approach involves three innovative pathways to improve the resolution of CZT radiation detectors: (1) implementation of high-barrier Schottky contacts to reduce the dark leakage current to an acceptable level; (2) post growth annealing treatments to eliminate precipitates and inclusions, which trap the electrons and limit the signals observed in the external circuitry; and (3) surface passivation by unique surface modifying treatments to reduce interfacial state densities to reduce leakage current. Commercial Applications and other Benefits as described by the awardee: The improved CZT based radiation detectors should be cost-effective and highly efficient, and should offer substantial performance advantages over existing gamma ray detectors. The CZT detector should be suitable for remote portable field applications including nuclear non-proliferation, national security, medical diagnostic imaging, environmental monitoring, and industrial inspection.