Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements, which is a very important and popular research direction at present. As a IV-V two-dimensional material, silicon phosphide (SiP) has obvious in-plane anisotropy and exhibits excellent optical and electrical anisotropy properties. Herein, the optical anisotropy of SiP is studied by spectrometric ellipsometry measurements and polarization-resolved optical microscopy, and its electrical anisotropy is tested by SiP-based field-effect transistor. In addition, the normal and anisotropic photoelectric performance of SiP is shown by fabricating a photodetector and measuring it. In various measurements, SiP exhibits obvious anisotropy and good photoelectric performance. This work provides basic optical, electrical, and photoelectric performance information of SiP, and lays a foundation for further study of SiP and applications of SiP-based devices.

Doping, which is the intentional introduction of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we present high-quality two-dimensional SnS₂ nanosheets with well-controlled Sb doping concentration via direct vapor growth approach and following micromechanical cleavage process. X-ray photoelectron spectroscopy (XPS) measurement demonstrates that Sb contents of the doped samples are approximately 0.22%, 0.34% and 1.21%, respectively, and doping induces the upward shift of the Fermi level with respect to the pristine SnS₂. Transmission electron microscopy (TEM) characterization exhibits that Sb-doped SnS₂ nanosheets have a high-quality hexagonal symmetry structure and Sb element is uniformly distributed in the nanosheets. The phototransistors based on the Sb-doped SnS₂ monolayers show n-type behavior with high mobility which is one order of magnitude higher than that of pristine SnS₂ phototransistors. The photoresponsivity and external quantum efficiency (EQE) of Sb-SnS₂ monolayers phototransistors are approximately three orders of magnitude higher than that of pristine SnS₂ phototransistor. The results suggest that the method of reducing Shottky barrier width to achieve high mobility and photoresponsivity is effective, and Sb-doped SnS₂ monolayer has significant potential in future nanoelectronic and optoelectronic applications.

Van der Waals (vdW) heterojunctions are equipped to avert dangling bonds due to weak, inter-layer vdW force, and ensure strong in-plane covalent bonding for two-dimensional layered structures. We fabricated four heterojunctions devices of different layers based on p-type distorted 1T-MX₂ ReSe₂ and n-type hexagonal MoS₂ nanoflakes, and measured their electronic and optoelectronic properties. The device showed a high rectification coefficient of 500 for the diode, a high ON/OFF ratio and higher electron mobility for the field-effect transistor (FET) compared with the individual components, and a high current responsivity (R_λ) and external quantum efficiency (EQE) of 6.75 A/W and 1, 266%, respectively, for the photodetector.