Phase-Dependent Band Gap Engineering in Alloys of Metal-Semiconductor Transition Metal Dichalcogenides

ORAL

Abstract

Bandgap engineering plays a critical role in optimizing the electrical and optical properties of semiconductors. Alloying can be used to tune band gaps by combining isovalent semiconductors. Here, we present a novel form of bandgap engineering involving alloying non-isovalent cations in a two-dimensional transition metal dichalcogenide [1]. By alloying semiconducting MoSe2 with metallic NbSe2, two structural phases of Mo0.5Nb0.5Se2, 1T and 2H, are produced, each with emergent electronic structure. At room temperature, the 1T and 2H phases are semiconducting and metallic, respectively. Electron diffraction patterns of the 1T structure show the presence of a nearly commensurate charge density wave (NCCDW). Density-functional theory calculations confirm that local distortions open a band gap in 1T-Mo0.5Nb0.5Se2 by facilitating charge transfer. In 2H-Mo0.5Nb0.5Se2, electrical transport measurements show a low-temperature transition to a commensurate CDW state with a bandgap. Our work expands the boundaries of alloy-based band gap engineering by using alloying to access CDW phases.

[1] S. Wang et al., Advanced Functional Materials (2020). https://doi.org/10.1002/adfm.202004912

*This work was supported by National Science Foundation (NSF) through grants: DMREF-1729787.

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Presenters

  • John Cavin

    • Washington University, St. Louis
    • Department of Physics, Washington University in St. Louis

Authors

  • Shuxi Wang

    • University of Illinois at Chicago

  • John Cavin

    • Washington University, St. Louis
    • Department of Physics, Washington University in St. Louis

  • Zahra Hemmat

    • University of Illinois at Chicago

  • Khagesh Kumar

    • University of Illinois at Chicago

  • Alexander Ruckel

    • University of Illinois at Chicago

  • Leily Majidi

    • University of Illinois at Chicago

  • Hamed Gholivand

    • University of Illinois at Chicago

  • Radwa Dawood

    • University of Illinois at Chicago

  • Jordi Cabana

    • University of Illinois at Chicago

  • Nathan P Guisinger

    • Argonne National Laboratory

  • Robert F Klie

    • University of Illinois at Chicago

  • Fatemeh Khalili-Araghi

    • University of Illinois at Chicago

  • Rohan Mishra

    • Department of Mechanical Engineering & Materials Science, Washington University in St. Louis
    • Institute of Materials Science & Engineering, Department of Mechanical Engineering & Materials Science, Washington University in St. Louis
    • Washington University, St. Louis
    • Institute of Materials Science and Engineering, Washington University in St. Louis
    • Institute of Materials Science & Engineering, Washington University, St. Louis

  • Amin Salehi-Khojin

    • University of Illinois at Chicago