Graphene quantum dots in fluorographene matrix formed by means of chemical functionalization

In the present study, we examined the creation conditions and the properties of graphene or multi-layer graphene (MLG) quantum dots (QDs) self-formed in insulating dielectric fluorographene matrix. The QD arrays were obtained using chemical functionalization of graphene or MLG films in an aqueous solution of hydrofluoric acid. The formation of a fluorographene network in the films caused their transition from conducting to insulating state; this transition was a result of partitioning of the films into isolated graphene islands accompanied by an increase of the resistance of the films by 7–8 orders of magnitude. Experimentally, it was shown that the characteristic time required for the formation of QD arrays in the films depended linearly on the initial film thickness, on the solution concentration, and on temperature. The atomic force microscopy lateral force measurements have allowed us to evaluate the sizes and densities of formed QDs, and to trace the evolution of both QDs and fluorinated barriers between them in the functionalization process. A possibility to achieve QD sizes ranging from 70–20 nm (at QD density ∼(4–6) × 1010 cm−2) to 10–20 nm (at QD density ∼1 × 1010 cm−2) has been demonstrated. The activation energies of electrical conductivity in the films with QDs have been evaluated.