Effect of differential bias on the transport of electrons in coplanar grid CdZnTe detectors

Segmented and pixilated electrode structures are used to compensate for poor hole transport in CdZnTe devices used for gamma-ray spectrometry and imaging. Efforts to model these structures have focused primarily on geometric effects; however, device performance also depends on the physical properties of the bulk and surface material, as well as the electrodes. In this paper, we describe experiments to characterize the electric field near the anode of a coplanar grid detector. The experiment is contrasted with a calculation that is based on an assumption commonly used to reduce the computational effort required to determine internal electric fields. Explanations for differences between the calculation and the experiment are proposed