SOI‐Based 2D WS ₂ (Yb)/Si vdW Heterojunction for Broadband and Super‐Responsive Photodetector

Abstract Transition metal dichalcogenides van der Waals (vdW) heterojunctions have important potential applications for the development of novel optoelectronic devices due to their unique structures and physical properties. However, it's inevitable to introduce pollutants during the preparation process of the heterojunction and device. Herein, 13.8at% of Yb‐doped monolayer WS ₂ (WS ₂ (Yb) is synthesized on a B‐doped Si/SOI substrate to form WS ₂ (Yb)/Si vdW heterojunctions using one‐step chemical vapor deposition (CVD) technique. The heterojunction device with an ultraclean interface is directly fabricated via the inkjet printing system. Density functional theory (DFT) calculations based on the WS ₂ (Yb)/Si heterojunction are performed, implying a type‐II band arrangement, which is conducive to the separation of electrons and holes. The absorption range of the heterojunction is expanded and enhanced to the short‐infrared of 2500 nm. Both semiconductors are theoretically predicted to be p‐type, and the carrier transport behaviors are consistent with the experimental results. Under a 635 nm monochromatic light illumination, the WS ₂ (Yb)/Si photodetector demonstrates 36.81 A W ⁻¹ of responsivity, 7203.59% of external quantum efficiency, 2.15 × 10 ¹² Jones of specific detectivity, 10 ³ of rectification ratio, and 10 ⁴ of photo‐to‐dark current ratio, respectively, indicating excellent optoelectronic performance. This provides a strategy to accelerate the development of 2D silicon‐based semiconductor integration.