Thickness-engineered CuInO₃ Perovskite Capping Layers for Stable Graphene/Silicon Schottky Photodetectors

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 CuInO₃ oxide perovskite nanoparticles (OPNPs) capping layer is introduced to overcome these issues. The CuInO₃ 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 × 10¹³ 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.