High-Performance Linear Polarization-Sensitive WSe ₂ /SnS _0.25 Se _0.75 Heterojunction Photodetectors: Synergy of Type-II Band Alignment and Gate-Modulated Anisotropic Transport

Linear polarization-sensitive photodetectors play a pivotal role in enhancing optical signal acquisition and suppressing stray light, thereby facilitating improved target detection and identification in complex environments such as low-light conditions and haze. Emerging two-dimensional (2D) in-plane anisotropic materials offer significant advantages for simplifying optical systems owing to their facile integration onto complex architectures and superior photodetection capabilities. In this work, we report the fabrication of a linear polarization-sensitive photodetector based on a WSe 2 /SnS 0.25 Se 0.75 van der Waals heterojunction. The electrical conductivity anisotropy between the armchair and zigzag directions in the WSe 2 /SnS 0.25 Se 0.75 heterojunction can be dynamically tuned via gate modulation, with values ranging from less than 1 to as high as 257. Furthermore, polarization-dependent carrier transport measurements reveal a significant anisotropy in mobility with a ratio of μ armchair /μ zigzag reaching 2.76. The fabricated device exhibits high polarization sensitivity and remarkable photoresponse performance along the armchair orientation, including a responsivity of 2.57 A/W, a detectivity of 5.76 × 10 10 Jones, a rise/decay times of 2.86/2.24 ms, and a photocurrent anisotropic ratio of 7.8. These findings reveal the physical mechanisms in 2D anisotropic heterostructures and provide design principles for high-performance linear polarization-sensitive photodetectors.