Sub-microsecond x-ray imaging using hole-collecting Schottky type CdTe with charge-integrating pixel array detectors

Abstract

CdTe is increasingly being used as the x-ray sensing material in imaging\npixel array detectors for x-rays, generally above 20 keV, where silicon sensors\nbecome unacceptably transparent. Unfortunately CdTe suffers from polarization,\nwhich can alter the response of the material over time and with accumulated\ndose. Most prior studies used long integration times or CdTe that was not of\nthe hole-collecting Schottky type. We investigated the temporal response of\nhole-collecting Schottky type CdTe sensors on timescales ranging from tens of\nnanoseconds to several seconds. We found that the material shows signal\npersistence on the timescale of hundreds of milliseconds attributed to the\ndetrapping of a shallow trap, and additional persistence on sub-microsecond\ntimescales after polarization. The results show that this type of CdTe can be\nused for time resolved studies down to approximately 100 ns. However\nquantitative interpretation of the signal requires careful attention to bias\nvoltages, polarization and exposure history.\n