Electronic transport across quantum dots in graphene nanoribbons: Toward built-in gap-tunable metal-semiconductor-metal heterojunctions

TL;DR

This paper explores how embedding graphene quantum dots in nanoribbons creates tunable electronic gaps and metal-semiconductor-metal junctions, advancing the development of integrated graphene-based electronic devices.

Contribution

It demonstrates the formation of width-dependent transport gaps and transition regimes in graphene quantum dot heterojunctions, providing a pathway for self-contained carbon-based electronics.

Findings

Width-dependent transport gaps enable tunable electronic properties.

Transition from antiresonant to resonant conductance near band edges.

Quantum confinement and dot-lead coupling influence transport regimes.

Abstract

The success of all-graphene electronics is severely hindered by the challenging realization and subsequent integration of semiconducting channels and metallic contacts. Here, we comprehensively investigate the electronic transport across width-modulated heterojunctions consisting of a graphene quantum dot of varying lengths and widths embedded in a pair of armchair-edged metallic nanoribbons, of the kind recently fabricated via on-surface synthesis. We show that the presence of the quantum dot enables the opening of a width-dependent transport gap, thereby yielding built-in one-dimensional metal-semiconductor-metal junctions. Furthermore, we find that, in the vicinity of the band edges, the conductance is subject to a smooth transition from an antiresonant to a resonant transport regime upon increasing the channel length. These results are rationalized in terms of a competition between quantum-confinement effects and quantum dot-to-lead coupling. Overall, our work establishes graphene quantum dot nanoarchitectures as appealing platforms to seamlessly integrate gap-tunable semiconducting channels and metallic contacts into an individual nanoribbon, hence realizing self-contained carbon-based electronic devices.