Resonant and Bound States of Charged Defects in Two-Dimensional Semiconductors

ORAL

Abstract

A detailed understanding of charged defects in two-dimensional semiconductors is needed for the development of ultrathin electronic devices. Here, we study negatively charged acceptor impurities in monolayer WS2 using a combination of scanning tunnelling spectroscopy and large-scale atomistic electronic structure calculations. We observe several localized defect states of hydrogenic wave function character in the vicinity of the valence band edge. Some of these defect states are bound, while others are resonant. The resonant states result from the multi-valley valence band structure of WS2, whereby localized states originating from the secondary valence band maximum at Γ hybridize with continuum states from the primary valence band maximum at K/K'. Resonant states have important consequences for electron transport as they can trap mobile carriers for several tens of picoseconds.

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Presenters

  • Johannes Lischner

    Imperial College London

Authors

  • Johannes Lischner

    Imperial College London

  • Martik Aghajanian

    Imperial College London

  • Bruno Schuler

    Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Laboratory

  • Katherine Cochrane

    Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Laboratory

  • Jun-Ho Lee

    Lawrence Berkeley National Laboratory, Physics, UC Berkeley

  • Christoph Kastl

    Technical University Munich, Lawrence Berkeley National Laboratory

  • Jeffrey B Neaton

    Lawrence Berkeley National Laboratory, Physics, UC Berkeley, Kavli Energy Nanoscience Institute at Berkeley, Physics, University of California, Berkeley, Department of Physics, University of California, Berkeley, University of California, Berkeley; Molecular Foundry, Lawrence Berkeley National Laboratory; Kavli Energy Nanosciences Institute at Berkeley, University of California, Berkeley, Lawrence Berkeley National Lab

  • Alexander Weber-Bargioni

    Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Laboratory

  • Arash A Mostofi

    Imperial College London, Departments of Materials and Physics, and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, Departments of Materials and Physics, and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK