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 MoTe 2 /WSe 2 /Cl–SnSe 2 unipolar barrier heterostructure. The WSe 2 layer acts as an efficient majority‐carrier‐blocking barrier, effectively suppressing dark current and achieving a room‐temperature specific detectivity of 6.75 × 10 8 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.