title: Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2.
abstract: We demonstrate the continuous and reversible tuning of the optical band gap of suspended monolayer MoS2 membranes by as much as 500 meV by applying very large biaxial strains. By using chemical vapor deposition (CVD) to grow crystals that are highly impermeable to gas, we are able to apply a pressure difference across suspended membranes to induce biaxial strains. We observe the effect of strain on the energy and intensity of the peaks in the photoluminescence (PL) spectrum and find a linear tuning rate of the optical band gap of 99 meV/%. This method is then used to study the PL spectra of bilayer and trilayer devices under strain and to find the shift rates and Grüneisen parameters of two Raman modes in monolayer MoS2. Finally, we use this result to show that we can apply biaxial strains as large as 5.6% across micron-sized areas and report evidence for the strain tuning of higher level optical transitions.
authors: Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215 United States.
authors: David
authors: D
authors: Lloyd
authors: Department of Mechanical Engineering, University of Colorado , Boulder, Colorado 80309 United States.
authors: Xinghui
authors: X
authors: Liu
authors: Department of Physics, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
authors: Jason W
authors: JW
authors: Christopher
authors: Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215 United States.
authors: Lauren
authors: L
authors: Cantley
authors: Department of Materials and Metallurgy, PEC University of Technology , Chandigarh, India 160012.
authors: Anubhav
authors: A
authors: Wadehra
authors: Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215 United States.
authors: Brian L
authors: BL
authors: Kim
authors: Department of Physics, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
authors: Bennett B
authors: BB
authors: Goldberg
authors: Department of Electrical and Computer Engineering, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
authors: Anna K
authors: AK
authors: Swan
authors: Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215 United States.|Division of Materials Science and Engineering, Boston University , Brookline, Massachusetts 02446 United States.
authors: J Scott
authors: JS
authors: Bunch
keywords: MoS2; Raman spectroscopy; Strain engineering; bandgap; biaxial strain; photoluminescence