Improved Infrared Imaging of Bulk Defects in CdZnTe Wafers

An improved method of infrared imaging of bulk defects in cadmium zinc telluride (CdZnTe) wafers has been developed. The method is intended primarily to be a means of identifying those portions of large CdZnTe wafers that are suitable to be "mined" for use in fabricating focal-plane arrays of photodetectors for x-ray and g-ray astronomy. Suitable portions are those that exhibit acceptably high degrees of uniformity of x-ray spectral response. The present method of infrared imaging is useful for identifying the suitable portions because, as described below, there is a correlation between (1) x-ray spectral responses and (2) infrared images of bulk defects that affect those responses.