Electrostatic Gating and Transport Studies of Thin Films of the 3D Dirac Semimetal Cd3As2

ORAL

Abstract

3D Dirac semimetals are an unusual class of quantum materials with unique electronic states. Topological transitions have been predicted as a result of confinement, symmetry breaking, and by the application of external electric fields. Here, we present transport studies of Cd3As2 films under external electric and magnetic fields.
To fabricate devices for electrostatic gating, 20 nm Al2O3 gate dielectrics were deposited on epitaxial Cd3As2 films using atomic layer deposition (ALD). An increase in sheet carrier density and decrease in mobility were observed after ALD. Capacitance-voltage characteristics show a small change in capacitance with gate bias, suggesting that the carrier modulation is occurring only at the Cd3As2/Al2O3 interface. The modulated carrier density is ~3x1013 cm-2. Field effect devices show a 12% modulation in drain current.
Hall measurements show a decrease in sheet carrier density with negative gate bias. At large negative gate bias, the Hall resistance suggests a two-carrier transport, as expected if the Fermi level is near the Dirac node. Moreover, a negative to positive magnetoresistance transition is observed when gate voltage is changed from positive to negative voltage. We discuss the results in terms of the nature of the electronic states in this system.

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Presenters

  • Omor Shoron

    Materials Department, University of California Santa Barbara

Authors

  • Omor Shoron

    Materials Department, University of California Santa Barbara

  • David Kealhofer

    Department of Physics, University of California Santa Barbara, Univ of California - Santa Barbara, Physics, University of California, Santa Barbara, Department of Physics, University of California, Santa Barbara

  • Manik Goyal

    ENMT, Materials Department, Univeristy of California Santa Barbara, Univ of California - Santa Barbara, Materials Department, University of California Santa Barbara

  • Timo Schumann

    ENMT, Materials Department, Univeristy of California Santa Barbara, Univ of California - Santa Barbara, Materials, University of California, Santa Barbara, Material Science, University of California, Santa Barbara, Materials Department, University of California Santa Barbara

  • Luca Galletti

    ENMT, Materials Department, Univeristy of California Santa Barbara, Materials, University of California, Santa Barbara, Materials Department, University of California Santa Barbara

  • Susanne Stemmer

    ENMT, Materials Department, Univ of California - Santa Barbara, Univ of California - Santa Barbara, UC Santa Barbara, ENMT, Materials Department, Univeristy of California Santa Barbara, Materials, University of California, Santa Barbara, Material Science, University of California, Santa Barbara, Materials Department, University of California Santa Barbara, Materials Department, Univ of California - Santa Barbara, Materials, Univ of California - Santa Barbara, Materials, Univ of California, Santa Barbara