(Invited) Non-Covalent Functionalization of Epitaxial Graphene for Atomic Layer Deposition of Dielectric Oxides

The successful integration of graphene with dielectric materials is an important step in the development of high-performance graphene-based nanoelectronics. For optimal performance, dielectric layers on graphene need to be ultrathin, conformal, and the growth process needs to be well-controlled and reproducible. In practice, atomic layer deposition (ALD) – a thin film growth process that utilizes self-limiting surface reactions for digital thin film thickness control – is an industrially relevant route to grow dielectric films and nanostructures for electronic applications. However, the chemical inertness and hydrophobicity of graphene typically cause direct ALD processes to yield films of poor quality (defected, non-uniform, and poorly adhered), thereby limiting the ultimate device performance. The key to successful integration of graphene and ALD film growth resides, therefore, in the ability to tailor the graphene surface in such a way that it is amenable to ALD chemistries, but in a manner that does not perturb the properties of the graphene itself. Here, we utilize non-covalently functionalized monolayers to seed uniform film growth by ALD as well as to facilitate directed growth of dielectric nanostructures, such as nanowire arrays. We specifically highlight the use of synchrotron characterization, including X-ray surface scattering and grazing-incidence small-angle scattering, to assess the influence that the functional layers have on thin film, interfacial, and nanoscale structure.