Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 45: Frontiers of Electronic-Structure Theory: Focus on the Interface Challenge VI (joint session O/CPP/DS/TT)

TT 45.11: Vortrag

Mittwoch, 3. April 2019, 17:30–17:45, H9

Mechanically tuned conductivity of graphene grain boundaries from first-principles calculations — Delwin Perera, •Jochen Rohrer, and Karsten Albe — Institut für Materialwissenschaft, Technische Universität Darmstadt, Germany

Nanocrystalline graphene has recently been shown to have a strong piezoresistivity and strain gauge factors that are notably higher compared to single- or microcrystalline graphene [1]. The origin of the enhanced piezoresistivity in nanocrystalline graphene is still not fully understood, but several theoretical works suggest that grain boundaries are the main cause as these can evoke transport gaps.

In our work we test this assumption with density functional theory based transport calculations of graphene bicrystals. In particular, we extend our analysis of the interplay between grain boundary structure and transport properties [2] by including mechanical strain. We compute transmission functions and current-voltage curves and compare them with tight binding calculations. Our findings suggest that the strain-induced transport gap modulation can be fully described by the response of the bulk graphene band structure towards strain.
[1] Riaz et al., Nanotechnology 26, 325202 (2015)
[2] Perera et al., Phys. Rev. B 98, 155432 (2018)