High Gain Derived from Facile Carrier Dynamics Manipulation for Sensitive X‐ray Detection and Imaging

Abstract

AbstractSignal amplification is vitally important for sensing low‐dose X‐rays in medical diagnosis by amplifying the generated electric read‐out signal. However, the complexity of external amplification circuits hampers device miniaturization and portability, while integrating amplification functionality directly into sensors or detectors remains a significant and formidable challenge. In this work, a direct high‐gain X‐ray detector with facile electron drift speed manipulation is reported in perovskite single‐crystal film (SCF). By employing laser‐assisted nucleation, high‐quality MAPbBr3 SCF is fabricated with precise control of thickness from ≈20 to ≈500 µm and the area up to 3 by 2 cm, while the architecture of ITO/MAPbBr3/Au is constructed to form the Schottky junction in opposite polarity. With the assistance of applied bias, the space electric field over MAPbBr3 SCF can be tunable, which ensures the manipulation of charge carrier drift speed to form recirculation for internal gain. The resultant photodetector exhibits an ultrahigh sensitivity of 1.44 × 105 µC Gy−1 cm−2 with a gain of 5.14 × 105, an ultralow detection limit of 39.8 nGy s−1, and the X‐ray array imaging is achieved at a low dose rate of 5 µGy s−1. These results confirm the advance of high‐gain detectors in constructing sensing arrays for practical safe medical diagnosis.