TCAD simulation studies of novel geometries for CZT ring-drift detectors

Abstract

In this work, technology computer-aided design (TCAD) simulation results of new CZT ring-drift detector geometries are presented. The physics model was developed and validated against the results from an existing device which had been comprehensively characterised at x-ray wavelengths. The model was then applied to new detector geometries and a systematic study of the parameters influencing charge collection performed. A comparison between one- two- and three-ring circle and semi-rectangular (or squircle) geometries is presented. In was found that charge collection with the squircle ring configuration was systematically better than the circular configuration and extends approximately 200 μm further from the collecting anode. In addition, a two-ring geometry device is shown to collect charge 400 μm and 250 μm further from the anode when compared to one- and three- ring geometries, respectively. Based on these results, we derive an optimum configuration which potentially can be multiplied on larger crystals, offering an increased charge collection volume without compromising energy resolution.