CdZnTe material uniformity and coplanar-grid gamma-ray detector performance

"Electron-only" detection techniques such as the coplanar-grid method are e ffective in overcoming some of the charge transport problems of CdZnTe and, consequently, have led to large-volume gamma-ray detectors with good energ y resolution while operating at room temperature. A requirement for the suc cess of these techniques is uniformity in electron generation and transport . Once large inhomogeneities in these properties caused by grain boundaries and other large-scale crystal defects are eliminated through simple materi al screening techniques, small variations remain and limit the gamma-ray en ergy resolution. In this paper we present the results from our characteriza tion and analysis of these nonuniformities in commercially available CdZnTe , and we establish the relationship between the nonuniformities and the ult imate coplanar-grid gamma-ray detector performance through experimental mea surements.