Nanoscale electrical characterization of graphene contacts to AlGaN/GaN heterostructures

In this paper, we describe a highly reproducible method to transfer graphene (Gr) grown on copper by chemical vapour deposition to the surface of AlGaN/GaN heterostructures and we report a nanoscale electrical characterization of current transport at Gr contact to AlGaN. This latter investigation has been carried out using local current-voltage measurements by conductive atomic force microscopy (CAFM), performed both on the Gr-coated and bare AlGaN surface (reference). These analyses provide information on the lateral uniformity of the Schottky barrier height (SBH) between Gr and AlGaN. Gr contacts to AlGaN exhibit much more uniform and significantly lower SBH (similar to 0.4 eV) than common metals, such as gold, with SBH similar to 0.96 eV. These results can be useful for future applications in high frequency transistors based on AlGaN/GAN heterostructures and Gr. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim