Conductance Asymmetry of Graphene p-n Junction

Tony Low, Purdue University
Seokmin Hong, Purdue University
Joerg Appenzeller, Birck Nanotechnology Center, Purdue University
Supriyo Datta, Birck Nanotechnology Center and Purdue University
Mark S. Lundstrom, School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University

Abstract

We use the nonequilibrium Green function method in the ballistic limit to provide a quantitative description of the conductance of graphene p-n junctions-an important building block for graphene electronics devices. In this paper, recent experiments on graphene junctions are explained by a ballistic transport model, but only if the finite junction transition width D-omega is accounted for. In particular, the experimentally observed anomalous increase in the resistance asymmetry between n-n and n-p junctions under low source/drain charge density conditions is also quantitatively captured by our model. In light of the requirement for sharp junctions in applications such as electron focusing, we also examine the p-n junction conductance in the regime where D-omega is small and find that wave-function mismatch (so-called pseudospin) plays a major role in sharp, p-n junctions.

Discipline(s)

Nanoscience and Nanotechnology