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Koos A.A.,Institute of Technical Physics and Materials Science | Koos A.A.,Korean Hungarian Joint Laboratory for Nanosciences KHJLN | Vancso P.,Institute of Technical Physics and Materials Science | Vancso P.,Korean Hungarian Joint Laboratory for Nanosciences KHJLN | And 14 more authors.
Carbon | Year: 2016

Heterostructures of 2D materials are expected to become building blocks of next generation nanoelectronic devices. Therefore, the detailed understanding of their interfaces is of particular importance. In order to gain information on the properties of the graphene - MoS2 system, we have investigated MoS2 sheets grown by chemical vapour deposition (CVD) on highly ordered pyrolytic graphite (HOPG) as a model system with atomically clean interface. The results are compared with results reported recently for MoS2 grown on epitaxial graphene on SiC. Our STM study revealed that the crystallographic orientation of MoS2 sheets is determined by the orientation of the underlying graphite lattice. This epitaxial orientation preference is so strong that the MoS2 flakes could be moved on HOPG with the STM tip over large distances without rotation. The electronic properties of the MoS2 flakes have been investigated using tunneling spectroscopy. A significant modification of the electronic structure has been revealed at flake edges and grain boundaries. These features are expected to have an important influence on the performance of nanoelectronic devices. We have also demonstrated the ability of the STM to define MoS2 nanoribbons down to 12 nm width, which can be used as building blocks for future nanoelectronic devices. © 2016 Elsevier Ltd. All rights reserved. Source


Nemes-Incze P.,Institute of Technical Physics and Materials Science | Nemes-Incze P.,Korean Hungarian Joint Laboratory for Nanosciences KHJLN | Tapaszto L.,Institute of Technical Physics and Materials Science | Tapaszto L.,Korean Hungarian Joint Laboratory for Nanosciences KHJLN | And 12 more authors.
Applied Surface Science | Year: 2014

The properties of graphene nanoribbons are dependent on both the nanoribbon width and the crystallographic orientation of the edges. Scanning tunneling microscope lithography is a method which is able to create graphene nanoribbons with well defined edge orientation, having a width of a few nanometers. However, it has only been demonstrated on the top layer of graphite. In order to allow practical applications of this powerful lithography technique, it needs to be implemented on single layer graphene. We demonstrate the preparation of graphene nanoribbons with well defined crystallographic orientation on top of gold substrates. Our transfer and lithography approach brings one step closer the preparation of well defined graphene nanoribbons on arbitrary substrates for nanoelectronic applications. © 2013 Elsevier B.V. Source


Nemes-Incze P.,Institute of Technical Physics and Materials Science | Nemes-Incze P.,Korean Hungarian Joint Laboratory for Nanosciences KHJLN | Vancso P.,Institute of Technical Physics and Materials Science | Vancso P.,Korean Hungarian Joint Laboratory for Nanosciences KHJLN | And 14 more authors.
Carbon | Year: 2013

Perturbations of the two dimensional carbon lattice of graphene, such as grain boundaries, have significant influence on the charge transport and mechanical properties of this material. Scanning tunneling microscopy measurements presented here show that localized states near the Dirac point dominate the local density of states of grain boundaries in graphene grown by chemical vapor deposition. Such low energy states are not reproduced by theoretical models which treat the grain boundaries as periodic dislocation-cores composed of pentagonal-heptagonal carbon rings. Using ab initio calculations, we have extended this model to include disorder, by introducing vacancies into a grain boundary consisting of periodic dislocation-cores. Within the framework of this model we were able to reproduce the measured density of states features. We present evidence that grain boundaries in graphene grown on copper incorporate a significant amount of disorder in the form of two-coordinated carbon atoms. © 2013 Elsevier Ltd. All rights reserved. Source

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