Low dark current and high stability X-ray detector based on FAPbI3/Ga2O3 heterojunction

Abstract

X-ray detectors have drawn great attention due to their wide applications in medical imaging and industrial inspection. Lead halide perovskite exhibits excellent X-ray detection merits because of its high-Z element and outstanding photoelectric properties. However, the perovskite-based X-ray detectors exhibit poor stability, low resistivity and large dark leakage current due to the soft lattice and ion migration of perovskite materials. Herein, we used Ga2O3 compact layer to form a heterojunction structure with formamidinum lead iodide (FAPbI3) to largely ease these issues. Compared with the bare FAPbI3 detector, the dark current of the FAPbI3/Ga2O3 heterojunction detector is reduced by 3 orders of magnitude and the photo-to-dark current ratio (PDCR) increased by 31-fold. The detection limit of 0.23 mGys−1 is obtained which is 20 times lower than the FAPbI3 detector and short response time of 20 ms is obtained. More importantly, the FAPbI3/Ga2O3 device exhibits better repeatability due to the suppression of ion migration by Ga2O3. This work provides an effective strategy to obtain low dark current and stable perovskite-based photodetector.