A study on the low energy X/γ-ray spectral response of CdZnTe planar detectors

Three CdZnTe planar detectors, named CZT1, CZT2 and CZT3 respectively, were fabricated based on the as-grown CdZnTe wafers grown with different dopant conditions. The low energy X/γ-ray spectral responses of the detectors were obtained under various electrical field strengths at room temperature. The energy resolution of the detectors was evaluated by combining the charge transport properties of the materials and the dopant behaviors. The deep level trapping centers of Cd_i²⁺ have been tentatively recognized as the electron trapping centers, hence deteriorating the resolution. Low In concentration doped CZT2 exhibits excellent X/γ-ray spectral resolution and charge transport properties, which implies a lower density of trapping centers in the crystal. In Al doped CZT3, however, a critically uncompleted charge carrier collection and in turn the reduced energy resolution is likely attributed to the scattering of the ionized aluminum interstitial Al_i.