Quantum-confined electronic states in atomically well-defined graphene nanostructures

• Published in: Physical review letters Vol. 107; no. 23; p. 236803
• Main Authors: Hämäläinen, Sampsa K, Sun, Zhixiang, Boneschanscher, Mark P, Uppstu, Andreas, Ijäs, Mari, Harju, Ari, Vanmaekelbergh, Daniël, Liljeroth, Peter
• Format: Journal Article
• Language: English
• Published: United States 30.11.2011
• ISSN: 1079-7114
• DOI: 10.1103/physrevlett.107.236803

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 on an Ir(111) substrate by low-temperature scanning tunneling microscopy and spectroscopy. We measure the atomic structure and local density of states 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 textbook "particle-in-a-box" problem applied to relativistic massless fermions.