Stabilization of Mercuric Iodide Using Titanium and Silicon Oxides

Abstract

Digital x-ray detectors consist of a conversion material, which converts incident radiation to an electrical signal, as well as a read-out circuit that is used to detect the electrical signal. Research is being conducted in order to improve their performance across various fields. In particular, many studies have explored the conversion materials to address the limitations of amorphous selenium (a-Se) currently in use and to develop alternative materials. Mercuric iodide (HgI₂) is one of the alternative materials being considered as it has greater x-ray sensitivity than a-Se and other candidate materials. This is due to its high atomic number and high x-ray absorption efficiency. It also had a high rate of electron-hole pair generation per particle due to its low pair creation energy. However, it is difficult to commercialize HgI₂ due to its high leakage current and unstable x-ray sensitivity. This study aims to resolve the disadvantages of HgI₂ by adding silicone dioxide (SiO₂), which is used as oxide film and insulating film in semiconductor processes, and titanium dioxide (TiO₂), which is used as an electrode in dye sensitizer solar cells. Detectors are fabricated for analysis using HgI₂, HgI₂-TiO₂, and HgI₂-SiO₂ unit-cells and the particle-in-binder method. SEM, dark current, and x-ray sensitivity measurements are used to compare their structural characteristics, electrical properties, and stability, respectively.