Aperiodic conductivity oscillations in quasi-ballistic graphene heterojunctions

TL;DR

This paper reports aperiodic conductivity oscillations in dual-gated graphene transistors, attributed to resonant tunneling through impurity states, highlighting a signature of Klein tunneling relevant for graphene nanoelectronics.

Contribution

It provides experimental evidence of aperiodic oscillations linked to impurity states, advancing understanding of quantum transport in graphene heterojunctions.

Findings

Oscillations are aperiodic and asymmetric.

Resonant tunneling explains the oscillation pattern.

Supports Klein tunneling as a fundamental phenomenon.

Abstract

We observe conductivity oscillations with aperiodic spacing to only one side of the tunneling current in a dual-gated graphene field effect transistor with an n-p-n type potential barrier. The spacing and width of these oscillatoins were found to be inconsistent with pure Farbry-Perot-type interferences, but are in quantitative agreement with theoretical predictions that attribute them to resonant tunneling through quasi-bound impurity states. This observation may be understood as another signature of Klein tunneling in graphene heterojunctions and is of importance for future development and modeling of graphene based nanoelectronic devices.