Preparation of indium tin oxide contact to n-CdZnTe gamma-ray detector

The nonmetal electrode material Indium Tin Oxide (ITO) has advantages of excellent conductivity, higher adhesion, and interface stability, showing potential to replace the metallic contacts for fabrication of CdZnTe (CZT) X/γ-ray detectors. In this work, high quality ITO electrodes for n-type CZT crystals were prepared by magnetron sputtering under a sputtering power of 75 W and a sputtering pressure of 0.6 Pa. A low dark current of ∼1 nA is achieved for the 5 × 5 × 2 mm³ ITO/CZT/ITO planar device under 100 V bias. The characteristics of Schottky contact are presented in the room temperature I-V curves, which are similar to those of the Au contact detectors. Based on the thermoelectric emission theory, the contact barrier and resistance of ITO electrodes are evaluated to be 0.902-0.939 eV and 0.87-3.56 × 10⁸ Ω, respectively, which are consistent with the values of the Au electrodes. The ITO/CZT/ITO structure detector exhibits a superior energy resolution of 6.5% illuminated by the uncollimated ²⁴¹Am @59.5 keV γ-ray source, which is comparable to the CZT detector with Au electrodes.