Carrier distribution and negative compressibility in graphene-MoS$_{2}$ heterostructures

ORAL

Abstract

We report the investigation of electrical properties and magnetotransport in monolayer graphene - multilayered MoS$_{2}$ heterostructures. The devices are fabricated by dry transfer of graphene layers onto exfoliated MoS$_{2}$. The conductivity dependence on the back-gate bias shows the ambipolar behavior characteristic of graphene, along with a marked saturation of the conductivity on the electron branch. Magnetotransport measurements reveal that the conductivity saturation is the result of electrons populating the lower mobility MoS$_{2}$ layer at a positive, threshold back-gate bias. Experimental data from heterostructures with different thicknesses allow the extraction of the band offset between the MoS$_{2}$ conduction band and the graphene charge neutrality point. Surprisingly, the carrier density in graphene reveals a marked decrease as a function of gate bias near the MoS$_{2}$ population threshold, an observation which implies that electrons in MoS$_{2}$ have negative compressibility at low carrier density.

*We thank ONR, Intel and NRI for their support.

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Authors

  • Stefano Larentis

    • The University of Texas at Austin

  • John R. Tolsma

    • Department of Physics, University of Texas at Austin
    • The University of Texas at Austin

  • Babak Fallahazad

    • The University of Texas at Austin

  • David C. Dillen

    • The University of Texas at Austin

  • Kyoung Kim

    • The University of Texas at Austin

  • Allan MacDonald

    • The University of Texas at Austin
    • Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USA
    • Department of Physics, The University of Texas at Austin, Austin, TX, 78712
    • Department of Physics, University of Texas at Austin
    • University of Texas at Austin
    • University of Texas at Austin, Austin, Texas 78712, USA
    • UT Austin
    • Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA

  • Emanuel Tutuc

    • The University of Texas at Austin