Stable Self-Powered Broadband PtSe2/Si Pin Infrared Photodetector Based on a High-Quality Ultrapure Intrinsic Si Film Exfoliated by Si/SOI Wafer Bonding

Two-dimensional (2D) PtSe₂ has attracted significant attention in recent years owing to its exceptional optoelectronic properties. Currently, the contact interface of the PtSe₂/bulk 2D-three-dimensional (3D) p-n heterojunction exhibits numerous defects. Moreover, the n-type bulk materials serve as a carrier transport layer, resulting in serious recombination losses and deterioration of device stability. In this study, a hydrophobic bonding is utilized to achieve bubble-free, high-strength, and oxide layer-free n⁺-Si/SOI wafer bonding, peeling off a high-quality, ultrapure i-Si layer to fabricate a novel p-PtSe₂/i-Si/n⁺-Si pin photodetector. The device demonstrates broad spectral detection capabilities ranging from 532 to 2200 nm, with a rectification ratio as high as 2.1 × 10⁵ and an ideal fitting value of 1 within a light power range of 3.5 mW. The responsivity (46.5 mA/W) and specific detectivity (1.94 × 10¹¹ Jones) exhibit minimal power dependence, demonstrating excellent stability. The ideality factor is as low as 1.2, close to the ideal state. The activation energy is nearly half of the Si band gap (0.52 eV), indicating a recombination mechanism for the carrier transport. This work successfully combines wafer bonding with 2D material transfer to construct van der Waals heterojunctions for the first time, offering a novel approach for the fabrication of 2D-3D Si-based pin photodetectors.