Effect of Internal Electrostatic Fields on Self‐Powered X‐Ray Detectors with High Sensitivity and Low Detection Limits in Polar Oxide Crystals α/ <i>β</i> ‐BaTeMo ₂ O ₉

Self-powered X-ray detectors enable operating without applying bias, enabling detector portability and making them highly valuable in the industrial and medical fields. This study demonstrates high-performance self-powered detectors using polar α-BaTeMo₂O₉ (α-BTM) and β-BaTeMo₂O₉ (β-BTM) oxide crystals. It is proven that the carriers are driven by the internal electrostatic field along the polar axis, and the internal electrostatic field has a favorable effect on the polar oxide crystal self-powered X-ray detector. The β-BTM self-powered detector has a sensitivity of 300.2 µCGy_air ^-1cm^-2 under 40 keV X-rays, which is 15 times that of α-Se detectors (20 µCGy_air ^-1cm^-2). The polar structure simultaneously addresses the inherent trade-off between dark current and photocurrent enhancement observed in conventional detectors. The polarization structure of α-BTM and β-BTM crystals leads to the macroscopic polarization along the polar axis, resulting in internal electrostatic fields of 34 and 66 V mm^-1. Furthermore, the ion activation energies of BTM are larger than 828 meV, which is higher than that of most perovskite materials, resulting in excellent stability and low dark current. The breakthrough performance stems from the synergistic effects of built-in polarization fields and robust crystalline structure, opening new avenues for portable radiation detection technologies.