Unipolar Barrier Near-Infrared 2D Photodetectors for 3D Image Sensors

Photodetectors sensitive to the near-infrared (NIR) range are of great importance for applications in machine vision, autonomous driving, and three-dimensional (3D) imaging under low-light or adverse weather conditions. Recently, two-dimensional (2D) semiconductors have emerged as promising light-absorbing materials for NIR detection. However, the inevitable majority-carrier injection from the electrode fundamentally leads to high dark current and poor light-detection capability, which has constrained the development of 2D semiconductor photodetectors so far. Here, we demonstrate a high-detectivity NIR photodetector based on a MoTe₂/WSe₂/Cl-SnSe₂ unipolar barrier heterostructure. The WSe₂ layer acts as an efficient majority-carrier-blocking barrier, effectively suppressing dark current and achieving a room-temperature specific detectivity of 6.75 × 10⁸ Jones, a linear dynamic range of 62 dB, and an effective -3 dB bandwidth approaching 0.1 MHz under 1310 nm illumination. Using this device as an imager, we show 3D NIR imaging of real objects under low-illumination conditions, highlighting its potential for applications such as vein visualization and material identification.