“Complementary Material Integration”: Co‐Optimizing Low Noise and High Signal in X‐Ray Detectors for High Detectivity via β ‐Ga 2 O 3 /3D/2D Metal Halide Perovskite Heterojunction

ABSTRACT Achieving high‐contrast imaging under low‐dose x‐rays is a core challenge for x‐ray detectors, as co‐optimizing low dark current and high sensitivity in a single material remains difficult. Herein, we propose a complementary material integration (CMI) strategy by combining a high resistivity wide bandgap oxide with a high µτ product perovskite. This strategy is demonstrated in the x‐ray detector based on a β ‐Ga 2 O 3 /3D/2D metal halide perovskite (MHP) heterostructure. The high resistivity of β ‐Ga 2 O 3 ensures low noise, while its combination with a 2D MHP layer effectively passivates the 3D MHP active layer, yielding both high performance and enhanced stability. The detector exhibits a large µτ product of 1.61 × 10 −3 cm 2 V −1 , a dark current of only 1.09 pA at 100 V, and a high sensitivity of 7140 µC Gy air −1 cm −2 . These properties yield a high quasi‐detectivity () of 354.86 C Gy −1 cm −1 A −1/2 and a low detection limit of 8.16 nGy s −1 . Furthermore, the detector realizes high‐contrast imaging (SNR = 138.0) for x‐rays at the medically safe dose (2.944 µGy s −1 ). This study successfully realizes the co‐optimization of low dark current, high sensitivity, and low detection limit, and provides a CMI strategy for high‐performance x‐ray imaging devices.