Defect-curing function of self-limiting Al2O3 thin films in graphene materials

Impedance spectroscopy was applied to 2-dimensional graphene materials that were thermally grown on copper substrates to quantitatively monitor the quality of the as-grown graphene materials without the subsequent transfer process. The presence of the graphene layer prevents the dissolution of the metallic copper elements in the corrosive electrolyte and provides an interface between the ionic electrolyte and electronic graphene/copper materials. The highest impedance appears at the graphene/electrolyte to be associated with electrochemically robust graphene materials, i.e., the as-grown graphene materials subjected to atomic layer deposition of Al2O3. Such an effect is attributed to the anti-corrosive protection of graphene materials and the defect-curing function of Al2O3 in graphene materials. The impedance-based information can be exploited in-situ without the use of any destructive approaches to evaluate the electrical perfectness vulnerable to preparation environments.