Quantum confined electronic states in atomically well-defined graphene nanostructures

TL;DR

This study investigates quantum confined electronic states in atomically precise graphene quantum dots with well-defined zigzag edges, using advanced microscopy and spectroscopy techniques, supported by theoretical modeling.

Contribution

It provides detailed experimental characterization and theoretical modeling of quantum states in graphene nanostructures with atomic precision, advancing understanding of their electronic properties.

Findings

Quantum states resemble relativistic particle-in-a-box solutions.

Atomic structure and LDOS vary with size and shape.

Results align with tight-binding and relativistic wave equation models.

Abstract

Despite the enormous interest in the properties of graphene and the potential of graphene nanostructures in electronic applications, the study of quantum confined states in atomically well-defined graphene nanostructures remains an experimental challenge. Here, we study graphene quantum dots (GQDs) with well-defined edges in the zigzag direction, grown by chemical vapor deposition (CVD) on an iridium(111) substrate, by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). We measure the atomic structure and local density of states (LDOS) of individual GQDs as a function of their size and shape in the range from a couple of nanometers up to ca. 20 nm. The results can be quantitatively modeled by a relativistic wave equation and atomistic tight-binding calculations. The observed states are analogous to the solutions of the text book "particle-in-a-box" problem applied to relativistic massless fermions.