Theoretical study of the interaction of electron donor and acceptor molecules with monolayer WS2. (16th June 2015)

• Record Type: Journal Article
• Authors: Zhou, C J; Yang, W H; Wu, Y P; Lin, W; Zhu, H L
• Is Part Of: Journal of physics. Volume 48:Number 28(2015)
• Publication Date: 2015-06-16
• Subjects: gas sensor -- transition metal dichalcogenides -- first-principles calculations; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/28/285303
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: With the aim of understanding recent experimental data concerning molecular doping in WS2 -based FET gas sensors, we have investigated the interaction of NH3 and H2 O molecules with monolayer WS2, by means of first-principles calculations. The structural relaxations and total energy calculations are performed to determine the preferential binding configurations and it is found that both NH3 and H2 O molecules are physisorbed on monolayer WS2 . The Bader analysis combined with the plane-averaged differential charge density results indicate that NH3 acts as the electron donor, while H2 O acts as the electron acceptor, leading to n- and p-type doping of WS2, respectively. The charge transfer mechanism is discussed in light of the mixing of the molecular highest occupied molecular orbital and lowest unoccupied molecular orbital with the underlying WS2 orbitals. In addition, the modification of the work function is found to be almost linearly dependent on the total charge transfer. The modification of the work function and the carrier concentration can be obtained by tuning the molecule coverages, without destroying the band structure of monolayer WS2 . The electrical sensitivities to the gas adsorption make WS2 a gas sensor that promises wide-ranging applications.