Tunnel transport in nitrogen-incorporated rippled graphene

Nano-Scale Transport Physics Laboratory, School of Physics, University of the Witwatersrand Private Bag 3, WITS 2050, Johannesburg, South Africa

^(a) Somnath.Bhattacharyya@wits.ac.za

Received: 2 July 2012
Accepted: 10 October 2012

Abstract

The specific effect of the interplay of defects such as vacancies, ripples and impurities on the electronic properties of graphene is investigated using the tight-binding Hamiltonian. While the transport gap increases with the vacancy concentration, the incorporation of impurities enhances the resonant states in the vicinity of the Fermi level (E_F). In addition to these defects, we find that the ripples, acting as multi-barrier structures on the graphene surface, can control the spread of delocalized states and the gap at E_F. Extreme rippling results in resonant states and weak negative differential resistance (NDR) features. By incorporating impurities (mainly clustered nitrogen that forms barriers) in the rippled graphene, the NDR signature can be controlled. Thus, we show a possible route for improvement of the tunnel current-voltage characteristics by incorporating nitrogen atoms in defective graphene which is applicable to switching devices.