Highly sensitive detection of polarized light using a new group IV–V 2D orthorhombic SiP

Group IV-V 2D semiconductors, such as GeP and GeAs, have attracted increasing attention as a hot research topic due to their high in-plane anisotropic properties. As one among them, orthorhombic SiP (o-SiP) deserves more attention due to its sufficiently high carrier mobility, large band gap, excellent stability and even a direct band gap in the monolayer. In this work, the experimental Raman modes were identified based on DFT calculations and then we demonstrated highly in-plane anisotropy of the phonon vibrations by angle-resolved polarized Raman spectroscopy. In addition, o-SiP based photodetectors were fabricated to investigate the in-plane anisotropic photoresponse. The results indicate that o-SiP is an alternative photodetector with high responsivity and well-reproducible cycles. Furthermore, high anisotropy was revealed with a notably anisotropic on/off switching ratio. Our results show that o-SiP is a new member of the family of group IV-V 2D semiconductors with intriguing optoelectronic properties, and will open new opportunities for promising applications in advanced photonic and optoelectronic devices.