Development of Hi-Z X-ray Detector

A postdoc level personal effort will be involved in evaluation of new semiconductors including cesium lead bromide for the purpose of room temperature X-ray radiation detection. The project aims to accelerate high energy radiation detector material discovery and evaluate materials for feasible application for X-ray imaging detector which requires innovative materials research. The project involves a wide range of research on cesium lead bromide solid crystal. The goal of this research is to evaluate the feasibility of the material in X-ray detector applications. The research will be conducted by multi-step material process including synthesis and purification, a large scale (250 g mass, >2.5 cm crystal diameter) crystal growth by Bridgman method, and characterization by the spectroscopic, charge transport, and photocurrent measurements. Specific research tasks he will be involved are as follows. 1) Development of Material synthesis and Crystal Growth: this task includes synthesis and crystal growth of cesium lead bromide semiconductor and optimization of the processes to achieve high quality single crystals by the least chemical steps and low cost. Optimization of crystal growth using Bridgman technique for large crystals is performed. 2) Assessment of Optoelectrical Properties and Detection Performance: Sample preparation (cutting and polishing) is performed for evaluation. The crystals are screened by photoluminescence, resistivity and X-ray photocurrent measurements. Chemical stability and mechanical properties of the crystals are also assessed. 3) Device Fabrication and Evaluation: detector fabrication with the detector grade crystals of cesium lead bromide is performed. The task requires large size of single crystals for fabrication of minimum ten detectors with 64x64 (140 micron pitch) pixels from one crystal batch. The detectors are integrated with ASIC (Application Specific Integrated Circuit) for final evaluation for X-ray imaging detector applications.