First-principles study of rectifying and switching behavior for different contact positions between sulfur-terminated armchair graphene nanoribbons junctions

¹ Department of Civil and Architectural Engineering, City University of Hong Kong - Kowloon, Hong Kong
² Department of Mechanical Engineering, University of Wisconsin - Milwaukee, WI 53211, USA
³ School of Physics and Electronic Science, Changsha University of Science and Technology Changsha 410114, PRC

Received: 20 December 2013
Accepted: 4 March 2014

Abstract

Transport properties of armchair graphene nanoribbon junctions with different widths are investigated on the zigzag edges terminated with sulfur atoms. The first-principles calculations based on the non-equilibrium Green's functions together with the density-functional theory show that their characteristics display obvious rectifying performance and switching behavior which are sensitive to the contact points and external activation. The analysis of the Mulliken charge distribution and projected Hamiltonian energy spectrum provides an inside view of the electronic structure of the ground state. The non-equilibrium states analysis, incorporating the density of states and projected density of states as well as the evolutions of frontier orbitals under various external biases, reveals that the intrinsic origin of the different rectifying performances is a result of the asymmetric movement of conducting states and contributing orbitals.