High-resolution mapping of the mobility–lifetime product in CdZnTe using a nuclearmicroprobe

Abstract

We present frontal ion beam induced charge imaging on a cadmium zinctelluride device using a 2.05 MeV He microbeam. Two sets of voltage-dependent3 mm × 3 mm scans over the device cathode were acquired at room temperature and 250 K respectivelyand the corresponding charge collection efficiency (CCE) images extracted. The reductionof CCE due to electron transport with reduced bias voltage can be described using a simplifiedHecht equation. This allows us to measure the mobility–lifetime product for electrons(μeτe) and so producehigh-resolution μeτe images at 296 and 250 K. At 296 K, CCE values up to 96% were observed for an electric field of3570 V cm−1. In general, theCCE values at 250 K are lower than the comparable values at 296 K withμeτe decreasingfrom 4.7 × 10−4 to 1.2 × 10−4 cm2 V−1,about 1/4 of its original value. Additionally, we observe an increase in CCE at 250 K due to previousirradiation of the material, caused by partial filling of electron traps by the ionbeam.