Tunable band gap by chemical functionalization of the Sr2S monolayer from first-principles calculations

Abstract

In this work, the structure and stability of the monolayer Sr2S are studied using first principles calculations. The electronic properties are investigated for pure monolayer Sr2S and termination states in three different configurations with three factors of F, O, and, OH. It is found that the pure Sr2S structure is physically stable and electronically is a non-magnetic metal. The monolayer Sr2S response to fluoride, oxide and hydroxide is different for each configuration. The most stable configuration for this structure is I-Sr2SX2 (X = F, O, OH). By terminating the structure with -F and -OH for all three configurations, the structure becomes a semiconductor with a direct band gap at Γ-point, by terminating with an O atom the structure becomes a half-metal with 100% polarization. The calculations demonstrate that the terminated pure monolayer Sr2S is a promising material for the nanoelectronics and spintronic industries.