Simulation and characterization of polycrystalline mercuric iodide film detector based on coplanar grid electrode

•The (001)-oriented poly-HgI2 films are grown on ITO glass by HWPVD system.•Simulating the potential distribution of the coplanar-grid HgI2 detectors.•Optimizing the coplanar-grid electrode patterns varying the widths of grid and gap.•The device of high quality films has low leakage current and stable capacity.•The electrical characteristic of device verifies the feasible simulation of design.

Polycrystalline mercuric iodide films are being developed as a new detector technology for X-ray imaging at room temperature. 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 electrical properties of high quality polycrystalline HgI2 detector based on coplanar-grid electrode are investigated at room temperature. The HgI2 device of high quality polycrystalline films has low leakage current before X-ray radiation and stable capacity under low frequency. Different coplanar-grid electrode patterns are designed by varying the widths of grid and gap. The finite elements analysis is used to simulate the potential distribution of the coplanar-grid HgI2 device. The electrode design of pattern A (the width of grid is 150 μm and the width of gap is 500 μm) is the best. The electrical characteristic of coplanar-grid device using mask A verifies the feasible simulation of electrode design for pattern A.