Ultrafast Fully Depleted SnSe ₂ /MoTe ₂ /SnSe ₂ Heterostructure Photodetector for Near‐Infrared Next‐Generation Automatic Obstacle Avoidance Systems

Abstract

Abstract With the systematic evolution of Advanced Driver Assistance Systems, the automatic obstacle avoidance (AOA) module has emerged as a mission‐critical component in modern vehicular systems during the post‐Moore period. To realize this functionality, infrared photodetectors with high responsivity, detectivity, and rapid response are essential. Herein, a fully depleted, self‐powered near‐infrared (NIR) 2D photodetector based on the back‐to‐back type‐III SnSe 2 /MoTe 2 /SnSe 2 (SMS) vertical dual heterojunction instead of SnSe 2 /MoTe 2 single heterojunction is demonstrated. Through Sentaurus TCAD simulation and theoretical calculation, it is proven that the middle MoTe 2 layer in the SMS dual heterojunction is completely depleted. Benefiting from the effective separation of photoinduced carriers and the nanoscale vertical transmission distance through asymmetric dual built‐in electric fields, the SMS dual heterojunction achieves a specific detectivity (D * ) of 1.1 × 10 11 Jones and a notable responsivity of 889 mA per Wunder 808 nm illumination. More importantly, the device exhibits a fast response speed, with rise and decay times of 16/27 µs. These exceptional performance characteristics substantiate the device's strong applicability for high‐speed NIR sensing circumstances, enabling the successful implementation of an AOA system. This work prevails a universal strategy for designing next‐generation NIR photodetectors based on type‐III dual heterostructure architecture.