Ultralow Detection Limit and Anisotropic X‐Ray Detection Behaviors Based on A Novel Oxide KCsMoP2O9 Single Crystal

Abstract X‐ray detection has drawn great attention in industrial examination, medical imaging, scientific research, and beyond. Herein, the anisotropic X‐ray detection performances are investigated based on a novel oxide crystal KCsMoP 2 O 9 (KCMP). The large dielectric screening effect and 1D infinite chain structure consisting of MoO 6 octahedron and two PO 4 tetrahedrons are conducive to efficient carrier transport along the X‐direction, leading to a higher µτ (4.77 × 10 −3 cm 2 V −1 ) of X direction than that of Z direction (1.05 × 10 −4 cm 2 V −1 ). Additionally, the KCMP‐based X‐ray detector along the X direction shows weaker ion migration than that of the Z direction due to the large migration barrier of O 2− (8.0 eV) and high ion active energy (784.9 meV) along the X direction. Owing to the high resistivity (2.29 × 10 13 Ω cm), high µτ, high ion activation energy, suppressed ion migration, and ultralow dark current, the X‐ray detection performance of the KCMP detector along the X direction is superior to that of the Z direction. Specifically, the high sensitivity (131.2 µC Gy −1 cm −2 ) and ultralow detection limit (8.9 nGys −1 ) are achieved in the KCMP detector along the X direction. This work clarifies anisotropic engineering to enhance the X‐ray detection performance of oxide crystals and proposes a novel X‐ray detection crystal with an ultralow detection limit.