Low-temperature performance of an MBE-grown CdTe x-ray photoconductor detector

Photoconductor array devices were fabricated using molecular beam epitaxially (MBE) grown CdTe. The detectors are stable in the presence of hard x-rays, and they have been tested at room temperature for over a year without any noticeable degradation. The performance of the photoconductor was greatly improved when the detector was cooled using the Peltier effect. The uniformity of the 64 element linear array device was measured at various temperatures. We observed an exponential decrease of the photoconductor dark current with temperatures down to 200 degrees K. The dark current and noise of the array detector decreased by more than 3 orders of magnitude from 300 degrees K to 200 degrees K. As a result, the minimum sensitivity to x-ray photons was increased by nearly 3 orders of magnitude. Finally an x-ray transmission image was obtained using a single element MBE CdTe photoconductor at 230 degrees K.