Summary of HgCdTe 2D array technology in the UK

HgCdTe 2D arrays are needed in both medium (MW) and long (LW) wavebands for imaging, search, and track and guidance applications. Often the detector i s the performance-limiting component in the system, and it is necessary to use detectors with very low excess noise and few defective pixels. Normally the detector is cooled sufficiently to freeze-out thermally generated leak age currents, so the main interest is to understand the mechanisms that det ermine the general detector performance and the cause of defective pixels. This paper describes the detector technology and the ion beam junction-form ing process. The fundamental performance limits of homojunction HgCdTe tech nology and the doping levels needed to produce a detector with impact-ioniz ation limited performance are discussed. Extensive studies have been made o n defective pixels in long wavelength arrays and some technologies for redu cing them are described here. Defective pixels have been found to be associ ated with material dislocations crossing the p-n junction and a model has b een proposed for the noise-generating mechanism.