Intercalation of hafnium oxide between epitaxially-grown monolayer graphene and Ir(111) substrate

Intercalation of insulating materials between epitaxial graphene and the metal substrates is highly demanded to restore the intrinsic properties of graphene, and thus essential for the graphene-based devices. Here we demonstrate a successful solution for the intercalation of hafnium oxide into the interface between full-layer graphene and Ir(111) substrate. We first intercalate hafnium atoms beneath the epitaxial graphene. The intercalation of the hafnium atoms leads to the variation of the graphene moiré superstructure periodicity, which is characterized by low-energy electron diffraction (LEED) and low-temperature scanning tunneling microscopy (LT-STM). Subsequently, we introduce oxygen into the interface, resulting in oxidization of the intercalated hafnium. STM and Raman’s characterizations reveal that the intercalated hafnium oxide layer could effectively decouple the graphene from the metallic substrate, while the graphene maintains its high quality. Our work suggests a high- k dielectric layer has been successfully intercalated between high-quality epitaxial graphene and metal substrate, providing a platform for applications of large-scale, high-quality graphene for electronic devices.