▎ 摘　　要

This paper proposes a new graphene-based quantum-dot device structure, in which nanostructured graphene islands are perfectly isolated and metallic contacts are directly deposited onto them without constrictions. Such a configuration is expected to be free from disturbances resulting from the structural fluctuation of constrictions, and allows for direct contact with a nanostructured two-dimensional electron gas. Transport spectroscopy analysis of this device structure was performed, and its Coulomb blockade behavior at low temperatures was revealed. Irregular Coulomb diamonds are observed in these devices, which is an indication of the formation of a multiple-quantum-dot system.