Modeling and Verification of 1/f Noise Mechanisms in FAPbBr ₃ Single‐Crystal X‐Ray Detectors

ABSTRACT Perovskite‐based direct X‐ray detectors have several advantages of high sensitivity, high spatial resolution and high energy resolution, and perovskite single crystals have lower trap state density and better charge transport ability than polycrystalline materials, thus showing excellent performance in the field of X‐ray detection. However, current perovskite single crystal X‐ray detectors still have some defects, such as high dark current, large electronic noise stability resulting in poor energy spectrum resolution. Crucially, the microscopic origins of electronic noise—specifically the competition between surface and bulk defect contributions—remain under‐explored in perovskite X‐ray detectors. In this work, we demonstrate that surface‐trap‐induced carrier number fluctuations are the dominant mechanism in FAPbBr 3 Schottky devices, a conclusion supported by the distinct defect profiles revealed by Drive‐Level Capacitance Profiling (DLCP). This letter based on the analysis of carrier transport dynamics, an innovative 1/f noise model for perovskite single‐crystal detectors is established, quantitatively characterizing the correlation between the noise power spectrum and defect concentration and depth. Through noise contribution decomposition, it is found that the 1/f noise of the detector is the key noise source affecting the system's energy resolution. Further, by combining the noise voltage spectrum test and defect characterization experiments of FAPbBr 3 single‐crystal devices, the theoretical inference that surface defects are the dominant noise source is verified. This surface reconstruction effectively suppresses the trap‐assisted tunneling and carrier trapping events that fuel the 1/f noise power spectral density, ultimately leading to a record energy resolution of 2.97 keV for 59.5 keV gamma rays. Our work can provide scientific guidance for perovskite in areas such as energy spectrum detection and X‐ray detection.