Polar selenide single crystal LiGa0.5In0.5Se2 with a bulk photovoltaic effect for highly sensitive self-driven X-ray detection

Abstract

Self-driven X-ray detectors, featuring low energy consumption, compactness, and integrability, are essential in diverse applications including medical imaging, security, and industrial inspection. Unlike the conventional photovoltaic based on Schottky and p–n junctions, the bulk photovoltaic effect (BPVE) enables photoexcited carrier separation in homogeneous polar single crystals, providing a promising mechanism for self-driven X-ray detection. In this study, we present a polar selenide single crystal LiGa_0.5In_0.5Se₂ (LGISe) as a BPVE-driven material for self-driven X-ray detection. Large-sized, high-quality LGISe crystals were successfully grown using the Bridgman growth technique. Photoelectric experiments reveal that the polarization-induced BPVE along the polar c-axis in LGISe facilitates the separation of photoexcited carriers without an external electric field. Leveraging this mechanism, we fabricated LGISe-based self-driven X-ray detectors, achieving a high sensitivity of 354 μC Gy⁻¹ cm⁻² and a low detection limit of 125.5 nGy s⁻¹ at zero bias, displaying a clear imaging at a dose rate of 2.944 μGy s⁻¹. This study highlights the significant potential of LGISe crystals for self-driven X-ray detection and establishes a novel platform for polar selenide materials in next-generation radiation detection technologies.