High Performance Self‐Driven Polarization‐Sensitive Photodetectors Based on GeAs/InSe Heterojunction

Abstract The ability to detect linearly polarized light is essential in the field of angle‐dependent optoelectronics and polarization optical applications. To date, most polarization‐sensitive photodetectors are mainly based on single 2D anisotropic materials, which still suffer from the large dark current, from being external bias driven, and from low anisotropy ratio. To address these obstacles, we fabricated a van der Waals (vdW) GeAs/InSe heterojunction with type‐II band alignment achieving a high‐performance self‐driven polarization‐sensitive photodetector. The heterojunction exhibits excellent rectifying characteristics with a current rectification ratio exceeding 10³. By operating in photovoltaic mode at zero bias, the device shows a very low dark current of ∼0.1 picoampere, high photoresponsivity of 357 mA/W, and large photo‐switching ratio of 10³, yielding a high specific detectivity of 2 × 10¹¹ Jones and photoelectric conversion efficiency (PCE) up to 8%. Benefiting from the anisotropic structure of the GeAs components, the heterojunctions also exhibit self‐driven polarization‐sensitive photodetection with superior anisotropic photocurrent ratio of ∼18 which surpasses state‐of‐the‐art 2D based polarization‐dependent detectors. This work proposes an effective strategy utilizing the anisotropic/isotropic vdW heterojunctions to enable self‐powered and high‐performance polarization‐sensitive photodetectors, opening a new avenue towards the promising potential applications in polarization‐resolved electronics and photonics.