Computational study of a family of monolayer 2D semiconducting tellurides

Discovery and design of 2D materials with suitable band gaps and high carrier mobility is of vital importance for photonics, optoelectronics, and high-speed electronics. In this work, based on first principles calculations using density functional theory (DFT) with PBE and HSE functionals, we introduce a family of monolayer isostructural semiconducting telluride M₂N₂Te₈ with M = {Ti, Zr, Hf} from group IV and N= {Si, Ge} from group XIV of periodic table. These compounds have been identified to possess direct band gaps that are tunable from 1.0 eV to 1.3 eV which are well suited for photonics and optoelectronics applications. Additionally, anisotropic in-plane transport behavior is observed and small electron and hole (0.11 - 0.15 m_e) masses are identified along the dominant transport direction. High carrier mobility are observed in these compounds, which shows great promise for applications in high-speed electronic devices. Detailed analysis of electronic structures reveals the atomic origins of promising properties of this unique class of 2D telluride materials.