Quantum Dot Behavior in Graphene Nanoconstrictions

Graphene nanoribbons display an imperfectly understood transport gap. We measure transport through nanoribbon devices of several lengths. In long (>= 250 nm) nanoribbons we observe transport through multiple quantum dots in series, while shorter (<= 60 nm) constrictions display behavior characteristic of single and double quantum dots. New measurements indicate that dot size may scale with constriction width. We propose a model where transport occurs through quantum dots that are nucleated by background disorder potential in the presence of a confinement gap.