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Growth of large-scale graphene is still accompanied by imperfections. By means of a four-tip scanning tunneling and electron microscope (4-tip STM/SEM), the local structure of graphene grown on SiC(0001) was correlated with scanning electron microscope images and spatially resolved transport measurements. The systematic variation of probe spacings and substrate temperature has clearly revealed two-dimensional transport regimes of Anderson localization as well as of diffusive transport. The detailed analysis of the temperature dependent data demonstrates that the local on-top nano-sized contacts do not induce significant strain to the epitaxial graphene films. [ABSTRACT FROM AUTHOR]

Direct imaging of atomic step morphologies and individual threading dislocations in on-axis epitaxial 4H-SiC surfaces is presented. Topographically sensitive electron images of the crystalline surfaces were obtained through forescattered electron detection inside a conventional scanning electron microscope. This technique, termed electron channeling contrast imaging (ECCI), has been utilized to reveal the configuration of highly stepped, homoepitaxial 4H-SiC films grown on 4H-SiC mesa structures. Individual threading dislocations have been consistently imaged at the core of spiral atomic step morphologies located on the 4H-SiC surfaces. The ability of ECCI to image atomic steps was verified by atomic force microscopy. [ABSTRACT FROM AUTHOR]