Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 73: Graphene: Structure (O with HL/TT)

HL 73.8: Talk

Thursday, March 19, 2015, 12:15–12:30, MA 041

Increasing the mobility of holes in graphene FETs by irradiation with swift heavy ions — •Tobias Foller, Philipp Ernst, Oliver Ochedowski, Roland Kozubek, Lukas Madauß, and Marika Schleberger — Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, 47048 Duisburg, Germany

In this work graphene field-effect transistors (FETs) are modified by irradiation with swift heavy ions (SHI, Xe²³⁺ with E_kin=91 MeV). Graphene FETs are prepared by exfoliation of a HOPG crystal followed by deposition of metal contacts via Photolithography. They allow to investigate the mobility of charge carriers in graphene. Current measurements, Raman spectroscopy and atomic force microscopy have been used to investigate the electrical and structural modifications of graphene due to the ion irradiation. By irradiation with swift heavy ions under perpendicular incidence with small fluences (≈ 2500 ions/µ m ²), we have succeeded in almost doubling the mobility of holes compared to the unirradiated sample.On the other hand irradiation under glancing incidence (≤ 2^∘) with fluences of 10 ions/µ m² have revealed that, despite the rather small changes in the (I_D/I_G)-ratio in the Raman spectrum, the charge carrier mobility is significantly reduced.