Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 28: 2D materials: Chalcogenides I (joint session HL/DS)
HL 28.12: Talk
Wednesday, March 14, 2018, 12:30–12:45, A 151
Persistent photoconductivity in monolayer MoS2 field effect transistors after UV irradiation — •Antony George1, Mikhail Fistul2,3, Uwe Hübner4, Nirul Masurkar5, David Kaiser1, Christof Neumann1, Andreas Winter1, Arava Leela Mohana Reddy5, and Andrey Turchanin1 — 1Friedrich Schiller University Jena, Institute of Physical Chemistry, 07743 Jena, Germany — 2Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 34051, Republic of Korea — 3Russian Quantum Center, National University of Science and Technology "MISIS", 119049 Moscow, Russia — 4Leibniz Institute of Photonic Technology, 07745 Jena, Germany — 5Department of Mechanical Engineering, Wayne State University, 48202 Detroit, USA
We demonstrate long living photo-excited charge carriers in monolayer MoS2 field effect transistors (FET) after UV irradiation. After irradiation, the FETs were found to be remaining in a high conductivity state at room temperature (RT) for a long time (ca. 30 days). We investigated the origin of the persistent photoconductivity (PPC) combining RT and low-temperature transport measurements with theoretical modeling. At low temperatures, a great enhancement of photo-induced conductivity with applied gate voltage was observed. We ascribe this to the UV irradiation of MoS2, which results in inter-band transitions and the creation of a large number of electron-hole pairs, which are quickly spatially separated due to local variations of the band structure. Under such conditions, the recombination time drastically increases and induces the PPC effect.