Atomic layer deposition of HfO₂ on graphene through controlled ion beam treatment

The polymer residue generated during the graphene transfer process to the substrate tends to cause problems (e.g., a decrease in electron mobility, unwanted doping, and non-uniform deposition of the dielectric material). In this study, by using a controllable low-energy Ar⁺ ion beam, we cleaned the polymer residue without damaging the graphene network. HfO₂ grown by atomic layer deposition on graphene cleaned using an Ar⁺ ion beam showed a dense uniform structure, whereas that grown on the transferred graphene (before Ar⁺ ion cleaning) showed a non-uniform structure. A graphene-HfO₂-metal capacitor fabricated by growing 20-nm thick HfO₂ on graphene exhibited a very low leakage current (<10^-11 A/cm²) for Ar⁺ ion-cleaned graphene, whereas a similar capacitor grown using the transferred graphene showed high leakage current.