Effect of disorder on a graphene p-n junction

TL;DR

This paper develops a theoretical framework for understanding transport in gate-tunable graphene p-n junctions, highlighting the roles of disorder and impurity density in determining diffusive versus ballistic behavior.

Contribution

It introduces a comprehensive theory linking carrier density gradients and impurity effects to transport regimes in graphene p-n junctions, and assesses experimental feasibility.

Findings

Ballistic transport conditions are marginally satisfied in current devices.

Disorder and impurity density critically influence junction resistance.

Simulations reveal challenges in achieving delicate ballistic effects like Veselago lensing.

Abstract

We propose the theory of transport in a gate-tunable graphene p-n junction, in which the gradient of the carrier density is controlled by the gate voltage. Depending on this gradient and on the density of charged impurities, the junction resistance is dominated by either diffusive or ballistic contribution. We find the conditions for observing ballistic transport and show that in existing devices they are satisfied only marginally. We also simulate numerically the trajectories of charge carriers and illustrate challenges in realizing more delicate ballistic effects, such as Veselago lensing.