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.

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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