title: Pressure-dependent optical and vibrational properties of monolayer molybdenum disulfide.
abstract: Controlling the band gap by tuning the lattice structure through pressure engineering is a relatively new route for tailoring the optoelectronic properties of two-dimensional (2D) materials. Here, we investigate the electronic structure and lattice vibrational dynamics of the distorted monolayer 1T-MoS2 (1T') and the monolayer 2H-MoS2 via a diamond anvil cell (DAC) and density functional theory (DFT) calculations. The direct optical band gap of the monolayer 2H-MoS2 increases by 11.7% from 1.85 to 2.08 eV, which is the highest reported for a 2D transition metal dichalcogenide (TMD) material. DFT calculations reveal a subsequent decrease in the band gap with eventual metallization of the monolayer 2H-MoS2, an overall complex structure-property relation due to the rich band structure of MoS2. Remarkably, the metastable 1T'-MoS2 metallic state remains invariant with pressure, with the J2, A1g, and E2g modes becoming dominant at high pressures. This substantial reversible tunability of the electronic and vibrational properties of the MoS2 family can be extended to other 2D TMDs. These results present an important advance toward controlling the band structure and optoelectronic properties of monolayer MoS2 via pressure, which has vital implications for enhanced device applications.
authors.affiliation: Department of Electrical and Computer Engineering, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Avinash P
authors.initials: AP
authors.lastname: Nayak
authors.forename: Tribhuwan
authors.initials: T
authors.lastname: Pandey
authors.forename: Damien
authors.initials: D
authors.lastname: Voiry
authors.forename: Jin
authors.initials: J
authors.lastname: Liu
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Moran
authors.forename: Ankit
authors.initials: A
authors.lastname: Sharma
authors.forename: Cheng
authors.initials: C
authors.lastname: Tan
authors.forename: Chang-Hsiao
authors.initials: CH
authors.lastname: Chen
authors.forename: Lain-Jong
authors.initials: LJ
authors.lastname: Li
authors.forename: Manish
authors.initials: M
authors.lastname: Chhowalla
authors.forename: Jung-Fu
authors.initials: JF
authors.lastname: Lin
authors.forename: Abhishek K
authors.initials: AK
authors.lastname: Singh
authors.forename: Deji
authors.initials: D
authors.lastname: Akinwande
keywords: 2D Materials; Diamond Anvil Cell; Hydrostatic Pressure; MoS2; Photoluminescence; Pressure Engineering; Strain; Transition Metal Dichalcogenide