Sub-Microsecond X-Ray Imaging Using Hole-Collecting Schottky type CdTe with Charge-Integrating Pixel Array Detectors

• Main Authors: Becker, Julian, Tate, Mark W, Shanks, Katherine S, Philipp, Hugh T, Weiss, Joel T, Purohit, Prafull, Chamberlain, Darol, Gruner, Sol M
• Format: Journal Article
• Language: English
• Published: 15-05-2017
• Subjects: Physics - Instrumentation and Detectors
• DOI: 10.48550/arxiv.1703.02106

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