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Atomically Thin <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msub> <mml:mi>MoS</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:math> : A New Direct-Gap Semiconductor

Kin Fai MakDepartment of Physics, Columbia University, New York, New York 10027, USAChanggu LeeSKKU Advanced Institute of Nanotechnology (SAINT) and Department of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746, KoreaJames HoneDepartment of Mechanical Engineering, Columbia University, New York, New York 10027, USAJie ShanDepartment of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USATony F. HeinzDepartments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA

2010lv

ABI

Annotatsiya

The electronic properties of ultrathin crystals of molybdenum disulfide consisting of N=1,2,…,6 S-Mo-S monolayers have been investigated by optical spectroscopy. Through characterization by absorption, photoluminescence, and photoconductivity spectroscopy, we trace the effect of quantum confinement on the material's electronic structure. With decreasing thickness, the indirect band gap, which lies below the direct gap in the bulk material, shifts upwards in energy by more than 0.6 eV. This leads to a crossover to a direct-gap material in the limit of the single monolayer. Unlike the bulk material, the MoS₂ monolayer emits light strongly. The freestanding monolayer exhibits an increase in luminescence quantum efficiency by more than a factor of 10⁴ compared with the bulk material.

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Identifikatorlar

DOI: 10.1103/physrevlett.105.136805

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