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MM: Fachverband Metall- und Materialphysik

MM 34: Nanomaterials

MM 34.4: Vortrag

Mittwoch, 14. März 2018, 12:30–12:45, H 0106

Influence of local grain boundary structure on electronic transport in polycrystalline graphene — •Delwin Perera, Jochen Rohrer, and Karsten Albe — Institut für Materialwissenschaft, Technische Universität Darmstadt, Germany

Graphene is a promising material for microelectronics and sensor technology due to its high charge carrier mobility, high strength and optical transparency. Recently, it was found that nanocrystalline graphene is piezoresistive which makes it suitable for strain sensing [1]. Theoretical studies attribute this piezoresistivity to grain boundaries, which can induce transport gaps. The size of the transport gap is believed to depend only on the misorientation of adjacent grains [2].

Here, we investigate the effect of the local grain boundary structure on the electron transport properties of graphene. We use density functional theory together with the non-equilibrium Green’s functions formalism to calculate transmission functions and current-voltage curves within the ballistic approximation [3]. Our results show that the size of the transport gap is indeed not affected by local structural changes. However, the details of the transmission function are sensitive to the local grain boundary structure. Therefore, the current-voltage characteristics depend not only on the misorientation.
[1] Riaz et al., Nanotechnology 26, 325202 (2015)
[2] Kumar et al., Nano Lett. 12, 1362 (2012)
[3] Brandbyge et al., Phys. Rev. B 65, 165401 (2002)