Nanostructured graphene: challenges in fabrication and modeling

DIPC Seminars

Speaker

Antti-Pekka Jauho (CNG, DTU Nanotech, Denmark)

When

2015/03/09
13:00

Place

Donostia International Physics Center (DIPC). Paseo Manuel de Lardizabal, 4, Donostia

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Nanostructured graphene: challenges in fabrication and modeling A. P. Jauho, M. Settnes, S. R. Power, D. H. Petersen CNG, DTU Nanotech, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark Pristine graphene has no band gap which severely restricts its applications in electronic devices. A number of methods have been suggested to overcome this difficulty, including graphene nanoribbons, bilayer systems, or periodic external potentials. We have studied extensively another means of achieving sizable band gaps: periodic nanoscale perforations – also known as graphene antidot lattices (GAL). Recent years have witnessed significant progress in the fabrication of these structures, and we review some aspects of these developments. A quantum mechanical modelling of the lab-made systems provides many challenges due to the large number of atoms to be treated, as well as effects due to disorder resulting from the fabrication steps. Recent progress in the modelling efforts will be described [1]. Dual-probe measurements of single antidots or extended defects in graphene have recently been shown to yield a wealth of microscopic information about the scattering processes occurring in these structures, in particular if the probe separation is smaller than the dephasing length [2,3]. Here we report a generalization to much larger structures with feature sizes of tens of nanometers. Standard approaches would result in a prohibitive numerical cost, and we have developed a novel method for treating the boundary conditions [4]: the self-energies which describe the device-to-lead coupling are generalized to a “square-self-energy”, which allows a computational analysis of large area samples. As an example, we consider large antidots, as well as “nanoblisters” on graphene [5], and show that their electronic transport properties display a rich phenomenology. We also discuss the interplay between pseudomagnetic fields, and Friedel oscillations, which these systems may exhibit. This research is supported by the Danish National Research Foundation, Project No. DNRF58. [1] S. R. Power and A. P. Jauho, Phys. Rev. B 90 (2014) 115406. [2] M. Settnes et al, Phys. Rev. Lett 112 (2014) 096801. [3] M. Settnes et al, Phys. Rev. B 90 (2014) 035440. [4] M. Settnes et al, submitted to Phys. Rev. B . [5] J. S. Bunch et al, Nano Letters 8 (2008) 2458. (hosted by Thomas Frederiksen)