AVS 60th International Symposium and Exhibition
    Graphene and Other 2D Materials Focus Topic Monday Sessions
       Session GR+EM+NS+SP+TF-MoA

Paper GR+EM+NS+SP+TF-MoA2
Electrical Properties of Graphene on Non-Conventional Substrates

Monday, October 28, 2013, 2:20 pm, Room 104 B

Session: Electronic Properties and Charge Transport in 2D Materials
Presenter: R. Rojas Delgado, University of Wisconsin
Authors: R. Rojas Delgado, University of Wisconsin
F. Cavallo, University of Wisconsin
H. Xing, University of Notre Dame
M.G. Lagally, University of Wisconsin
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The excellent electrical-transport properties of graphene make it an outstanding candidate for electronic-device applications. Therefore continued improvements in these properties are being sought, especially as graphene contacts other materials. Theories have shown that charge carrier mobilities of the order of 104 - 109 cm2V-1s-1 for carrier densities of 1013-109 cm-2 should be possible on a free-standing sheet. Experiments have demonstrated values 105 - 107 cm2V-1s-1 at low temperatures (5-50K). Mobilities measured for graphene supported by dielectrics have been much lower (103 - 105 cm2V-1s-1), but the range of substrates explored has been quite limited. Here we suggest that semiconductor substrates may make good candidates for substrate-supported graphene-based devices. In particular, Ge appears to maintain a high mobility in graphene transferred and bonded to it. For graphene grown by CVD on Cu transferred to an almost intrinsic Ge(001) substrate with carrier density of 2x1013 cm-2 and resistivity of 55Ω-cm, we measure a mobility of 2x106 cm2 V-1s-1 at 20K and 2x105 cm2 V-1s-1 at 80K which is 1000 times higher than what we expect from bulk Ge(001). We discuss these results in terms of possible charge transfer at the graphene/Ge(001) interface. Research supported by DOE.