Junction‐Enhanced Polarization Sensitivity in Self‐Powered Near‐Infrared Photodetectors Based on Sb 2 Se 3 Microbelt/n‐GaN Heterojunction

Abstract Polarization‐sensitive photodetectors (PDs) based on anisotropic materials spark considerable interest for their potential applications in security surveillance, optical switches, and remote sensing. However, high‐thickness or bulk anisotropic materials generally exhibit low polarization sensitivity, hindering their practical applications in polarization photodetection. Herein, a near‐infrared (NIR) PD based on a p‐type Sb 2 Se 3 microbelt (MB)/n‐GaN heterojunction is proposed. The Sb 2 Se 3 MB/GaN PD effectively combines the anisotropy of the Sb 2 Se 3 MB with the heterogeneous integration. The PD presents self‐powered detection properties with a responsivity over 12 mA W −1 , a specific detectivity exceeding 5 × 10 10 Jones, and a response speed (the rising/decaying times ≈74 ms/75 ms) under NIR illumination. More importantly, the heterojunction‐based PD has a higher anisotropy ratio of 1.37, which is 1.3 times amplified as compared to the vertical photoconductive‐type PDs (the anisotropy ratio of 1.06). The p‐n junction's effect on carrier generation and recombination causes the increased polarization sensitivity of Sb 2 Se 3 MB/GaN PDs, as confirmed by finite element method analysis. This work not only offers a deeper insight into polarization sensitivity regulated by junction or interface but also provides a practical method for developing high‐sensitivity polarization detectors based on high‐thickness or bulk anisotropic materials.