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

Berger, Helmuth
Published in Applied physics letters. 2014, vol. 104, no. 17, 171112
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 conversionIonic liquidsField effect transistors
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Research groups Groupe Kuzmenko
Groupe Morpurgo
Groupe Van der Marel
Swiss National Science Foundation: Sinergia proposal on atomically thin transition metal dichalcogenides
Autre: Graphene Flagship
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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 https://archive-ouverte.unige.ch/unige:36286

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Deposited on : 2014-05-05

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