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Title: Scanning photocurrent microscopy reveals electron-hole asymmetry in ionic liquid-gated WS{sub 2} transistors

We perform scanning photocurrent microscopy on WS{sub 2} 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 WS{sub 2}.
Authors:
;  [1] ; ;  [1] ;  [2] ;  [3]
  1. DPMC, Université de Genève, 24 quai Ernest Ansermet, CH-1211 Geneva (Switzerland)
  2. (Switzerland)
  3. Institut de Physique de la Matière Condendée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)
Publication Date:
OSTI Identifier:
22267722
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 17; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; ASYMMETRY; DIFFUSION LENGTH; ELECTRONS; FIELD EFFECT TRANSISTORS; HOLES; MOLTEN SALTS; TUNGSTEN SULFIDES