Explosive recombination-enhanced Re defect migration in MoS$_{\mathrm{2}}$~

ORAL

Abstract

Via scanning transmission electron microscopy, substitutional Re impurities in MoS$_{\mathrm{2}}$ are observed to undergo exchanges with neighboring Mo atoms on a time scale of several seconds. Density functional theory calculations of multiple possible diffusion pathways predict~a large barrier that rules out thermal jumps and also rules out jumps induced by the electron beam because the energy transfer to Re is quite small. Microscopy further reveals that several S vacancies accompany Re atoms and that the initial and final configurations have different number and configurations of S vacancies. Density functional theory calculations find that the hydrogenic level of an isolated Re impurity becomes deep with small displacements of the Re atom and the S vacancies introduce additional deep levels so that the entire gap is filled with levels in constant motion. We propose that the observed jumps are the result of an ``explosive'' recombination-enhanced migration mechanism i.e., multiple electron-hole recombination events provide energy in multiples of the energy gap. The energy is transferred to local vibrations that ultimately cause the observed jumps.

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Authors

  • Weiwei Sun

    Vanderbilt University, USA

  • Shize Yang

    Oak Ridge National Laboratory, USA, Oak Ridge National Laboratory

  • Yuyang Zhang

    Vanderbilt University, Vanderbilt University, USA, Vanderbilt Univ, Department of Physics and Astronomy, Vanderbilt University

  • Yongji Gong

    Rice University, USA, Rice University, Houston

  • Pulickel Ajayan

    Rice University, USA, Rice University, Houston, Rice University

  • Matthew Chisholm

    Oak Ridge National Laboratory, USA, Oak Ridge National Laboratory

  • Wu Zhou

    University of Chinese Academy of Sciences, China, University of Chinese aca. of sci., Beijing

  • Sokrates T. Pantelides

    Vanderbilt University, Vanderbilt University, USA, Oak Ridge National Laboratory, USA, Vanderbilt University, Oak Ridge National Lab, Vanderbilt University, USA, Vanderbilt Univ., Department of Physics and Astronomy, Vanderbilt University, Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University