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Bandgap Engineering of Strained Monolayer and Bilayer MoS<sub>2</sub>

Hiram J. ConleyDepartment of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United StatesBin WangDepartment of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United StatesJed I. ZieglerDepartment of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United StatesRichard F. HaglundDepartment of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United StatesSokrates T. PantelidesDepartment of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United StatesKirill I. BolotinDepartment of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United States

2013en

ABI

Annotatsiya

We report the influence of uniaxial tensile mechanical strain in the range 0-2.2% on the phonon spectra and bandstructures of monolayer and bilayer molybdenum disulfide (MoS2) two-dimensional crystals. First, we employ Raman spectroscopy to observe phonon softening with increased strain, breaking the degeneracy in the E' Raman mode of MoS2, and extract a Grüneisen parameter of ~1.06. Second, using photoluminescence spectroscopy we measure a decrease in the optical band gap of MoS2 that is approximately linear with strain, ~45 meV/% strain for monolayer MoS2 and ~120 meV/% strain for bilayer MoS2. Third, we observe a pronounced strain-induced decrease in the photoluminescence intensity of monolayer MoS2 that is indicative of the direct-to-indirect transition of the character of the optical band gap of this material at applied strain of ~1%. These observations constitute a demonstration of strain engineering the band structure in the emergent class of two-dimensional crystals, transition-metal dichalcogenides.

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Identifikatorlar

DOI: 10.1021/nl4014748

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