Highly Sensitive Polarization Photodetection Using a Pseudo-One-Dimensional Nb_(1–x)Ti_xS₃ Alloy

Low-symmetry layered two-dimensional (2D) materials with strong in-plane optical anisotropy can potentially be applied for polarization photodetection. This is especially true for those 2D materials with a direct band gap, which can efficiently absorb light with specific axial polarization. However, discovering such new anisotropic 2D materials with a direct band structure is still extremely challenging. Here, we fabricate a photodetector using a pseudo-one-dimensional (pseudo-1D) Nb(1–x)TixS3 alloy device and demonstrate that it is highly sensitive to the polarized light because of the strong in-plane optical anisotropy and direct band gap of the alloy by combining angle-resolved polarization Raman spectroscopy, azimuth-dependent reflectance difference microscopy, polarization-dependent absorption spectroscopy, and hybrid functional theory calculations. As a consequence, the polarization photodetector of the Nb(1–x)TixS3 alloy shows a large photocurrent anisotropic ratio and a high photoresponse. The choice of a low-symmetry layered pseudo-1D Nb(1–x)TixS3 alloy in polarization photodetection might open up new functionalities for novel optoelectronic device applications.