Junction-Enhanced Polarization Sensitivity in Self-Powered Near-Infrared Photodetectors Based on Sb2Se3 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 Sb₂Se₃ microbelt (MB)/n-GaN heterojunction is proposed. The Sb₂Se₃ MB/GaN PD effectively combines the anisotropy of the Sb₂Se₃ 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 × 10¹⁰ 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 Sb₂Se₃ 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.