L. Britnell, R. V. Gorbachev, A. K. Geim, L. A. Ponomarenko, A. Mishchenko, M. T. Greenaway, T. M. Fromhold, K. S. Novoselov, L. Eaves
The chemical stability of graphene and other freestanding two-dimensional atomic crystals means that they can be stacked in different combinations to produce a new class of heterostructure materials, "tailor-made" for device applications. In this nascent technology, graphene is a versatile electrode due to its unique electronic spectrum and high quality, making it possible to change the carrier polarity, sheet density and chemical potential by applying a gate voltage. These properties have been exploited recently in multilayer heterostructure transistors with high on-off switching ratios. Here we demonstrate graphene transistors with gate-tuneable negative differential conductance. We explain this behaviour in terms of resonant tunnelling of carriers when the spectra of Dirac fermions in the two graphene electrodes are aligned. The nanoscale separation of the source and drain electrodes and the multi-valued current-voltage characteristics of our devices have potential for high frequency and logic applications.
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http://arxiv.org/abs/1303.6864
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