Surface morphology and electrical properties of polycrystalline mercuric iodide films based on coplanar grid electrode

Abstract

Polycrystalline mercuric iodide (HgI2) films have been grown on ITO-coated glass substrates using hot-wall physical vapor deposition (HWPVD) with the different source temperatures. The influence of source temperature on the structure and morphology of the polycrystalline HgI2 films is investigated. It is found that the source temperature plays an important role in the improvement of the structure and morphology. The uniformly (001)-oriented polycrystalline HgI2 films can be obtained at the source temperature of 85 °C. The electrical properties of high quality polycrystalline HgI2 films based on coplanar-grid electrode are investigated at room temperature under irradiation conditions by 5.9 keV X-ray irradiation from 55Fe source. For (001)-oriented polycrystalline HgI2 films, the dark current is in the order of 10−8 A and photo current is in the order of 10−7 A with the applied voltage of 40 V. However, a stable signal of capacity in the order of 10−12 F is also obtained under low and high frequency respectively.