Dr. Yihui He

Abstract:

Halide perovskite semiconductors for direct X- and gamma-ray detection have currently attracted enormous attention for medical imaging and nuclear nonproliferation in homeland security, featuring excellent charge transport properties and low cost. As previously evidenced the hole carriers in perovskite semiconductors have better transport properties than electrons carriers. The unipolar sensing strategy could eliminate such challenge induced by the electron trapping issue. However, the development of unipolar detectors for perovskite semiconductors is still at an early stage where substantial efforts are requested for the device optimization. Here, our progress on the unipolar perovskite detectors were reported with the configuration of pixelated and virtual Frisch grid type aiming at their deployment for the high energy resolution gamma-ray spectroscopy. The influence of guard ring electrode on the dark reduction was also investigated. The thickness of single-crystal detectors varied from ~several mm to centimeters which were grown by melt method. The relationship of the carrier drift time and the signal amplitude in various detector configurations were analyzed to estimate the charge transport properties of the whole carrier. The energy resolution was determined based on the signal amplitude analysis. The issues in achieving high energy resolution by unipolar perovskite semiconductors were also analyzed. These results shall be of interest in the applications of high-performance room temperature gamma-ray detectors.