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Scanning photocurrent microscopy reveals electron-hole asymmetry in ionic liquid-gated WS2 transistors

Contributors

Ubrig, Nicolas; Jo, Sanghyun; Berger, Helmuth; Morpurgo, Alberto; Kuzmenko, Alexey

Published in

Applied physics letters, vol. 104, no. 17, 171112

Publication date

2014

Abstract

We perform scanning photocurrent microscopy on WS2 ionic liquid-gated field effect transistors exhibiting high-quality ambipolar transport. By properly biasing the gate electrode, we can invert the sign of the photocurrent showing that the minority photocarriers are either electrons or holes. Both in the electron- and hole-doping regimes the photocurrent decays exponentially as a function of the distance between the illumination spot and the nearest contact, in agreement with a two-terminal Schottky-barrier device model. This allows us to compare the value and the doping dependence of the diffusion length of the minority electrons and holes on a same sample. Interestingly, the diffusion length of the minority carriers is several times larger in the hole accumulation regime than in the electron accumulation regime, pointing out an electron-hole asymmetry in WS2.

Keywords

  • Photoelectric conversion
  • Ionic liquids
  • Field effect transistors

UNIGE affiliation entities

UNIGE research groups

Funding

  • Swiss National Science Foundation - Sinergia proposal on atomically thin transition metal dichalcogenides
  • Autre - Graphene Flagship

Citation (ISO format)

UBRIG, Nicolas et al. Scanning photocurrent microscopy reveals electron-hole asymmetry in ionic liquid-gated WS2 transistors. In: Applied physics letters, 2014, vol. 104, n° 17, p. 171112. doi: 10.1063/1.4872002

Main files (1)

Article (Published version)

Identifiers

Additional URL for this publication

http://scitation.aip.org/content/aip/journal/apl/104/17/10.1063/1.4872002

Journal ISSN

0003-6951
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711downloads

Technical informations

Creation

02/05/2014 13:29:00

First validation

02/05/2014 13:29:00

Update

14/03/2023 21:11:23

Status update

14/03/2023 21:11:23

Last indexation

10/06/2025 21:40:20
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