Electric Current Focusing Efficiency in Graphene Electric Lens

TL;DR

This paper theoretically analyzes electron wave focusing in graphene pn junctions, revealing how current distribution depends on junction symmetry and providing design insights for graphene-based electric lenses.

Contribution

It introduces an analytical approach to study electron focusing in graphene pn junctions and derives current collection ratios for symmetric and npn junctions.

Findings

In symmetric PNJ, 25% of current is collected by the drain.

In symmetric npn junction, 18.75% of current is collected.

Provides a general design rule for negative refractive index systems.

Abstract

In present work, we theoretically study the electron wave's focusing phenomenon in a single layered graphene pn junction(PNJ) and obtain the electric current density distribution of graphene PNJ, which is in good agreement with the qualitative result in previous numerical calculations [Science, 315, 1252 (2007)]. In addition, we find that for symmetric PNJ, 1/4 of total electric current radiated from source electrode can be collected by drain electrode. Furthermore, this ratio reduces to 3/16 in a symmetric graphene npn junction. Our results obtained by present analytical method provide a general design rule for electric lens based on negative refractory index systems.