Moderate strain induced indirect bandgap and conduction electrons in MoS2 single layers

János Pető, Gergely Dobrik, Gergő Kukucska, Péter Vancsó, Antal A. Koós, János Koltai, Péter Nemes-Incze, Chanyong Hwang, Levente Tapasztó

Research output: Contribution to journalArticle

Abstract

MoS2 single layers are valued for their sizeable direct bandgap at the heart of the envisaged electronic and optoelectronic applications. Here we experimentally demonstrate that moderate strain values (~2%) can already trigger an indirect bandgap transition and induce a finite charge carrier density in 2D MoS2 layers. A conclusive proof of the direct-to-indirect bandgap transition is provided by directly comparing the electronic and optical bandgaps of strained MoS2 single layers obtained from tunneling spectroscopy and photoluminescence measurements of MoS2 nanobubbles. Upon 2% biaxial tensile strain, the electronic gap becomes significantly smaller (1.45 ± 0.15 eV) than the optical direct gap (1.73 ± 0.1 eV), clearly evidencing a strain-induced direct to indirect bandgap transition. Moreover, the Fermi level can shift inside the conduction band already in moderately strained (~2%) MoS2 single layers conferring them a metallic character.

Original languageEnglish
Article number39
Journalnpj 2D Materials and Applications
Volume3
Issue number1
DOIs
Publication statusPublished - Dec 1 2019

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ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanical Engineering
  • Mechanics of Materials
  • Condensed Matter Physics
  • Chemistry(all)

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