Two-dimensional silicon and carbon monochalcogenides with the structure of phosphorene

Phosphorene has recently attracted interest for applications in transistors and photodetectors. Inspired by this material we carried out an ab initio study to predict new binary materials with a structure similar to phosphorene. Specifically, carbon or silicon atoms and chalcogen atoms (up to Te) were combined to form a phosphorene-like monolayer. The structure of these new compounds was then optimized and the dynamical stability of the structures was demonstrated by computing phonon dispersion curves. A series of materials were found to be stable: CS, CSe, CTe, SiO, SiS, SiSe, and SiTe. Electronic properties such as band gaps and effective masses were computed at the density functional theory level. By using the accurate HSE hybrid functional it was found that these materials span a broad range of bandgaps, going from the 2.1 eV of SiS to the 0.55 eV of SiTe. The effective masses were also computed; similarly to phosphorene, a strong anisotropy was found when comparing the zigzag and armchair directions. The variety of electronic properties found for these systems will contribute to broaden the technological applicability of two dimensional materials.