期刊
NANO LETTERS
卷 17, 期 1, 页码 392-398出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.6b04344
关键词
Molybdenum disulfide; bilayer; electric-field-induced; second-harmonic generation; inversion symmetry breaking; interlayer coupling
类别
资金
- Deutsche Forschungsgemeinschaft (DFG) through the TUM International Graduate School of Science and Engineering (IGSSE)
- BMBF by Q.com [16KIS0110]
- German Excellence Initiative via the Nano systems Initiative Munich
- PhD program ExQM of the Elite Network of Bavaria
- European Graphene Flagship
We demonstrate pronounced electric-field induced second-harmonic generation in naturally inversion symmetric 2H stacked bilayer MoS2 embedded into micro capacitor devices. By applying strong external electric field perturbations (vertical bar F vertical bar = +/-2.6 MV cm(-1)) perpendicular to the basal plane of the crystal, we control the inversion symmetry breaking and, hereby, tune the nonlinear conversion efficiency. Strong tunability of the nonlinear response is observed throughout the energy range (E-omega similar to 1.25-1.47 eV) probed by measuring the second-harmonic response at E-2 omega, spectrally detuned from both the A- and B-exciton resonances. A 60-fold enhancement of the second-order nonlinear signal is obtained for emission at E-2 omega = 2.49 eV, energetically detuned by Delta E = E-2 omega - E-C = -0.26 eV from the C-resonance (E-C = 2.75 eV). The pronounced spectral dependence of the electric-field-induced second-harmonic generation signal reflects the bandstructure and wave function admixture and exhibits particularly strong tunability below the C-resonance, in good agreement with density functional theory calculations. Moreover, we show that the field-induced second-harmonic generation relies on the interlayer coupling in the bilayer. Our findings strongly suggest that the strong tunability of the electric-field-induced second-harmonic generation signal in bilayer transition metal dichalcogenides may find applications in miniaturized electrically switchable nonlinear devices.
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