Emerging Two-dimensional Group IV Chalcogenides as Building Blocks for Advanced Infrared Photodetector

Abstract

The recent synthesis of two-dimensional (2D) Te-Si-Si-Te monolayer with a four-atomic-layer-thick hexagonal lattice, has attracted significant interest for its potential in infrared (IR) applications. In this regard, we conduct density functional theory calculations and nonequilibrium Green’s function simulations to systematically explore the crystal structure, chemical bonds, electronic and optical properties of emerging 2D X-A-A’-X’ (X = Te, A = Si, A’ = Si, Ge, Sn, Pb and X’ = Se, Te), as well as the optoelectronic performance of their corresponding vdW heterostructures. The pictures for electronic structures, chemical bonding and optical features of the 2D X-A-A’-X’ are drawn. Their indirect, narrow-gap semiconducting nature, highly carrier mobility anisotropy and strong optical absorption are unraveled. Additionally, it is highlighting that Te-Si-Pb-Te/Sb2Te3, Te-Si-Si-Se/Sb2Te3, and Te-Si-Ge-Se/Sb2Te3-based p-i-n junctions exhibit remarkably high photocurrent density and photoresponsivity in the IR region, underscoring their potential applications as IR photodetector. Our work indicates that such emerging 2D group Ⅳ chalcogenides are potential building blocks for designing next-generation IR optoelectronic devices.