Thickness‐engineered CuInO ₃ Perovskite Capping Layers for Stable Graphene/Silicon Schottky Photodetectors

ABSTRACT The performance of graphene/silicon (Gr/Si) Schottky photodetectors is often limited by high dark current, inefficient carrier extraction, and poor stability. Here, a thickness‐tunable CuInO ₃ oxide perovskite nanoparticles (OPNPs) capping layer is introduced to overcome these issues. The CuInO ₃ OPNPs are synthesized via a microwave‐assisted thermal method, exhibiting high crystallinity and strong optical absorption. By tuning the layer thickness (201–1412 nm), an interfacial dipole is engineered, increasing the Schottky barrier height from 0.84 to 0.96 eV. This results in an 87.6% reduction in dark current and over 21‐fold enhancement in photocurrent under 405 nm illumination. The optimized device (201 nm) achieves a responsivity of 0.79 AW ⁻¹ , detectivity of 2.0 × 10 ¹³ Jones, EQE of 242%, and a low noise‐equivalent power of 7.97 × 10 ⁻¹⁴ W Hz ^−1/2 , with fast response times (0.126/0.127 ms). Thickness‐dependent analysis reveals that intermediate thickness balances electric field enhancement and carrier transport. The device also shows excellent stability, retaining ∼87% photocurrent after 30 days and stable operation over 500 cycles, demonstrating strong potential for high‐performance photodetectors. Furthermore, the engineered interface suppresses recombination, enhances carrier separation, and ensures efficient tunneling, contributing to improved signal‐to‐noise ratio and reliable long‐term device operation under ambient conditions without encapsulation for applications.