Probing defects in a small pixellated CdTe sensor using an inclined mono energetic X-ray micro beam

Frojdh, E. et al. (2013) Probing defects in a small pixellated CdTe sensor using an inclined mono energetic X-ray micro beam. IEEE Transactions on Nuclear Science, 60(4), pp. 2864-2869. (doi: 10.1109/TNS.2013.2257851)

Abstract

High quantum efficiency is important in X-ray imaging applications. This means using high-Z sensor materials. Unfortunately many of these materials suffer from defects that cause non-ideal charge transport. In order to increase the understanding of these defects, we have mapped the 3D response of a number of defects in two 1 mm thick CdTe sensors with different pixel sizes (55 μm and 110 μm) using a monoenergetic microbeam at 79 keV. The sensors were bump bonded to Timepix read out chips. Data was collected in photon counting as well as time-over-threshold mode. The time-over-threshold mode is a very powerful tool to investigate charge transport properties and fluorescence in pixellated detectors since the signal from the charge that each photon deposits in each pixel can be analyzed. Results show distorted electrical field around the defects, indications of excess leakage current and large differences in behavior between electron collection and hole collection mode. The experiments were carried out on the Extreme Conditions Beamline I15 at Diamond Light Source.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: O'Shea, Professor Val and Maneuski, Dr Dima
• Authors: Frojdh, E., Frojdh, C., Gimenez, E.N., Krapohl, D., Maneuski, D., Norlin, B., O'Shea, V., Wilhelm, H., Tartoni, N., Thungstrom, G., and Zain, R.M.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: IEEE Transactions on Nuclear Science
• Publisher: Institute of Electrical and Electronics Engineers
• ISSN: 0018-9499
• ISSN (Online): 1558-1578