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.