Position sensitive single carrier CdZnTe detectors

Single polarity charge sensing on room temperature semiconductor gamma-ray detectors can be achieved by using the coplanar electrode readout technique. This method can eliminate the hole trapping problem of the wide bandgap semiconductors which are currently available. Previous results on 5 mm cube CZT detectors confirmed that the energy resolution can be dramatically improved compared with that obtained using the conventional readout method. This paper explores the application of this technique to CdZnTe detectors of larger volume, namely 1 cubic cm. In our previous work, we suggested a method to obtain γ-ray interaction depth and further progress is reported here. This technique can be used to correct for the electron trapping as a function of distance from the anode. Some characteristics of this method have been studied and its advantages are discussed. The intrinsic position resolution has been analyzed and energy resolutions of less than 2% FWHM at 662 keV were obtained on both detectors tested. Finally, the factors which are inhibiting reaching the statistical limit of CdZnTe detectors have been explored. These results will be of interest in the design of higher performance, portable and imaging-related room-temperature semiconductor γ-ray detectors