Characterization of CdTe X-Ray Sensor Layer on Medipix Detector Chips

Abstract

We have been characterizing various sensor layers bump-bonded to Medipix detector chips. We report here characterizationthe leakage current variations of a cadmium telluride (CdTe) assembled-Medipix2 assemblyat different temperatures.Medipix detectors are being used in small animal computed tomography (CT) scanner systems known as MARS-CT. The spectroscopic imaging of a mouse and human atheroma using this system has previously been reported [1-2]. In those reports, Medipix2 detectors were used with Si and GaAs sensor layers, respectively. Cadmium telluride (CdTe) is expected to be a useful sensor layer for clinical CT imaging detectors because of its good detection efficiency for x-rays in the energy range up to 120 keV. However, Aan understanding of the detection characteristics of these sensor layers is vital to high-quality imaging. This work presents the results of inhomogeneities within the CdTe sensor, temperature variations and wrinkle pattern instability.We present leakage current variations with temperature and sensitivity inhomogeneity across the detector. This is an extension of the tests previously reported in Aamir R et al [1][3].