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arXiv · 1102.1718

Accurate six-band nearest-neighbor tight-binding model for the pi-bands of bulk graphene and graphene nanoribbons

Timothy B. Boykin·Mathieu Luisier·Gerhard Klimeck·Xueping Jiang·Neerav Kharche·Yu Zhou·Saroj K. Nayak
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Abstract

Accurate modeling of the pi-bands of armchair graphene nanoribbons (AGNRs) requires correctly reproducing asymmetries in the bulk graphene bands as well as providing a realistic model for hydrogen passivation of the edge atoms. The commonly used single-pz orbital approach fails on both these counts. To overcome these failures we introduce a nearest-neighbor, three orbital per atom p/d tight-binding model for graphene. The parameters of the model are fit to first-principles density-functional theory (DFT) - based calculations as well as to those based on the many-body Green's function and screened-exchange (GW) formalism, giving excellent agreement with the ab initio AGNR bands. We employ this model to calculate the current-voltage characteristics of an AGNR MOSFET and the conductance of rough-edge AGNRs, finding significant differences versus the single-pz model. These results show that an accurate bandstructure model is essential for predicting the performance of graphene-based nanodevices.

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Timothy B. Boykin, Mathieu Luisier, Gerhard Klimeck, Xueping Jiang, Neerav Kharche, Yu Zhou, Saroj K. Nayak. 2011-02-08. Accurate six-band nearest-neighbor tight-binding model for the pi-bands of bulk graphene and graphene nanoribbons. https://doi.org/10.1063/1.3582136

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