title: Electric-Field Switchable Second-Harmonic Generation in Bilayer MoS2by Inversion Symmetry Breaking.
abstract: We demonstrate pronounced electric-field-induced second-harmonic generation in naturally inversion symmetric 2H stacked bilayer MoS2embedded into microcapacitor devices. By applying strong external electric field perturbations (|F| = ±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 (Eω∼ 1.25-1.47 eV) probed by measuring the second-harmonic response at E2ω, 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 E2ω= 2.49 eV, energetically detuned by ΔE = E2ω- EC= -0.26 eV from the C-resonance (EC= 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.
authors.affiliation: Walter Schottky Institut and Physik Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: J
authors.identifier: 0000-0002-0873-8224
authors.initials: J
authors.lastname: Klein
authors.affiliation: Walter Schottky Institut and Physik Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wierzbowski
authors.affiliation: Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Steinhoff
authors.affiliation: Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Florian
authors.affiliation: Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany.|Bremen Center for Computational Materials Science, Universität Bremen , 28334 Bremen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Rösner
authors.affiliation: Lehrstuhl für Physik funktionaler Schichtsysteme, Physik Department E10, Technische Universität München , James-Franck-Straße 1, 85748 Garching, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Heimbach
authors.affiliation: Walter Schottky Institut and Physik Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Müller
authors.affiliation: Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Jahnke
authors.affiliation: Institut für Theoretische Physik, Universität Bremen , P.O. Box 330 440, 28334 Bremen, Germany.|Bremen Center for Computational Materials Science, Universität Bremen , 28334 Bremen, Germany.
authors.forename: T O
authors.initials: TO
authors.lastname: Wehling
authors.affiliation: Walter Schottky Institut and Physik Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: J J
authors.initials: JJ
authors.lastname: Finley
authors.affiliation: Walter Schottky Institut and Physik Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kaniber
keywords: Molybdenum disulfide; bilayer; electric-field-induced; interlayer coupling; inversion symmetry breaking; second-harmonic generation