Fast-response X-ray detector based on nanocrystalline Ga2O3 thin film prepared at room temperature

Abstract

X-ray detectors have broad applications in the fields of medical imaging, security checks, industrial inspections, and scientific research. However, it is still challenging to develop X-ray detectors with fast response, high sensitivity, and stable direct conversion. In this study, we fabricated a fast-response X-ray detector based on a nanocrystalline Ga2O3 thin film, prepared by electron beam evaporation without a high-temperature post-annealing process. The structure characterization results show that Ga2O3 films were nanocrystalline, and a coplanar metal/semiconductor/metal (MSM)-structured X-ray detector was fabricated. The detection sensitivity reached up to 138.80 μCmGyair−1 cm−3 (at 50 V bias voltage), and the dark current was 50 pA (at 10 V bias voltage). In addition, the rise time and fall time of the transient photocurrent were measured (<35 ms) at an X-ray dose rate of 28.79 mGyairs−1, and there was no distinct persistent photocurrent (PPC) effect. The low defect density arising from the good crystalline structure of the Ga2O3 thin films is the major reason for the fast response of the device. These results show that nanocrystalline Ga2O3 thin films are promising materials for large-area X-ray imaging.