Abstract
Based on the density functional theory (DFT), the electronic properties of O-doped pure and sulfur vacancy-defect monolayer WS2 are investigated by using the first-principles method. For the O-doped pure monolayer WS2, four sizes (2 × 2 × 1, 3 × 3 × 1, 4 × 4 × 1 and 5 × 5 × 1) of supercell are discussed to probe the effects of O doping concentration on the electronic structure. For the 2 × 2 × 1 supercell with 12.5% O doping concentration, the band gap of O-doped pure WS2 is reduced by 8.9% displaying an indirect band gap. The band gaps in 3 × 3 × 1 and 4 × 4 × 1 supercells are both opened to some extent, respectively, for 5.55% and 3.13% O doping concentrations, while the band gap in 5 × 5 × 1 supercell with 2.0% O doping concentration is quite close to that of the pure monolayer WS2. Then, two typical point defects, including sulfur single-vacancy (VS) and sulfur divacancy (V2S), are introduced to probe the influences of O doping on the electronic properties of WS2 monolayers. The observations from DFT calculations show that O doping can broaden the band gap of monolayer WS2 with VS defect to a certain degree, but weaken the band gap of monolayer WS2 with V2S defect. Doping O element into either pure or sulfur vacancy-defect monolayer WS2 cannot change their band gaps significantly, however, it still can be regarded as a potential method to slightly tune the electronic properties of monolayer WS2.
Highlights
Two-dimensional (2D) transition-metal dichalcogenides (TMD), such as MoS2, WS2 and others, have been widely studied because of their excellent properties in mechanics, electronics, optics and so on
We focus on the influences of oxygen (O) element on the electronic properties of both pure monolayer WS2 and two types of sulfur vacancy-defects monolayer WS2, including S
The electronic properties of O-doped pure and sulfur vacancy-defect WS2 monolayers are studied using first-principles calculations based on the density functional theory (DFT)
Summary
Department of Mechanical Engineering, Northwestern University, eVanston, IL 60208, USA School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350108, China Received: 23 November 2017; Accepted: 29 January 2018; Published: 31 January 2018
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