Photodetector based on Ta2NiS5/BP heterojunction

Abstract

In recent years, two-dimensional (2D) materials have gained attention in photodetection due to their unique energy band structures and excellent carrier transport properties. Anisotropic materials like black phosphorus (BP) and transition metal dichalcogenides, such as Ta2NiS5, offer opportunities for developing high-performance polarization-sensitive photodetectors, thanks to their tunable bandgap and remarkable optical anisotropy. This study successfully fabricates a mid-infrared polarization-sensitive photodetector using a BP/Ta2NiS5 van der Waals heterojunction, followed by an investigation of its photoelectric response under 3700 nm laser irradiation. The high-quality interface is achieved through mechanical exfoliation and precise dry transfer techniques, with metal electrodes created via electron beam lithography. Experimental results show that the detector achieves a maximum responsivity of 1.69 µA/W at zero bias, and the photogenerated current increases linearly within a specific bias voltage range. The device exhibits significant polarization dependence, with a polarization ratio of -0.81, attributed to the anisotropic behavior of the carriers at the heterojunction interface. This research offers insights into designing mid-infrared polarization detectors with anisotropic 2D materials and highlights the importance of the heterojunction interface in optoelectronic performance. The findings also suggest future research directions, including energy band modulation and interface defect engineering to enhance device performance.