Neutral Exciton Diffusion in Monolayer MoS2

Shiekh Zia Uddin, Hyungjin Kim, Monica Lorenzon, Matthew Yeh, Der-Hsien Lien, Edward S. Barnard, Han Htoon, Alexander Weber-Bargioni, Ali Javey

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

Monolayer transition metal dichalcogenides (TMDCs) are promising materials for next generation optoelectronic devices. The exciton diffusion length is a critical parameter that reflects the quality of exciton transport in monolayer TMDCs and limits the performance of many excitonic devices. Although diffusion lengths of a few hundred nanometers have been reported in the literature for as-exfoliated monolayers, these measurements are convoluted by neutral and charged excitons (trions) that coexist at room temperature due to natural background doping. Untangling the diffusion of neutral excitons and trions is paramount to understand the fundamental limits and potential of new optoelectronic device architectures made possible using TMDCs. In this work, we measure the diffusion lengths of neutral excitons and trions in monolayer MoS2 by tuning the background carrier concentration using a gate voltage and utilizing both steady state and transient spectroscopy. We observe diffusion lengths of 1.5 μm and 300 nm for neutral excitons and trions, respectively, at an optical power density of 0.6 W cm-2.

Original languageEnglish
Pages (from-to)13433-13440
Number of pages8
JournalACS Nano
Volume14
Issue number10
DOIs
StatePublished - 27 Oct 2020

Keywords

  • diffusion
  • exciton
  • MoS2
  • quantum yield
  • transport
  • trion

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