Engineering the Polarization Sensitivity in All‐2D Photodetectors Composed of Semimetal MoTe 2 and Semiconductor WS 2

The polarization sensitivity, defined as the photocurrent anisotropic ratio, is of high importance for the polarization‐sensitive photodetectors that determine the resolution and contrast of captured images. Conventional polarized light detectors utilizing optical filters suffer from complex fabrication and calibration processes. 2D materials with in‐plane anisotropic structures can serve to realize the detection of polarized light, yet the polarization sensitivity still remains poor, hampering practical implementations. In this work, highly sensitive polarized photodetectors are achieved by designing an all‐2D device architecture composed of anisotropic semimetal MoTe 2 and semiconductor WS 2 . In MoTe 2 /WS 2 heterojunction, the built‐in electric field at the interface between a semimetal and a semiconductor yields a strong photovoltaic effect, leading to a fast (≈45 µs) and polarization‐sensitive photodetection due to the anisotropic features of MoTe 2 . It is shown that MoTe 2 /WS 2 /MoTe 2 devices feature a polarization sensitivity of 13, a nearly five‐fold improvement by aligning the lattice orientation of side MoTe 2 from cross to parallel configurations. This work offers a new degree of freedom to engineer the polarization sensitivity and photodetection performance by optimizing crystal orientation in an all‐2D architecture comprising semimetal and semiconducting 2D materials.