High-Sensitivity Metal-Oxide-Semiconductor Graphene-InP Hybrid Photodetector with Enhanced Near-Infrared Detection Capability

Abstract We present a theoretically optimized metal–oxide–semiconductor (MOS) graphene–InP hybrid photodetector engineered for ultra‑sensitive near‑infrared (NIR) detection at the telecommunication wavelength of 1.55 µm. Building on the limitations of graphene–semiconductor Schottky devices—where high interface trap density degrades responsivity and elevates dark current—we introduce an ultrathin 3 nm atomic‑layer‑deposited Al₂O₃ interfacial layer between monolayer graphene and p‑type InP. This engineered barrier simultaneously passivates interface defects and enables efficient quantum tunneling of photocarriers, thereby enhancing carrier lifetime and suppressing thermionic emission. Comprehensive numerical simulations, combining drift–diffusion transport and WKB tunneling models, predict a responsivity of 2.3 A W⁻¹ at 2 V reverse bias, dark current of ~10⁻¹⁷ A, and specific detectivity exceeding 2 × 10¹³ Jones, with a −3 dB bandwidth of 18 GHz for a 4 µm active length. By tuning oxide thickness and gate bias, the device exhibits spectral sensitivity control over the entire 1.3–1.6 µm NIR window. These results demonstrate an interface‑engineering‑driven pathway toward low‑noise, high‑speed graphene photodetectors suitable for next‑generation optical communication and sensing systems.