Driving chemical interactions at graphene-germanium van der Waals interfaces via thermal annealing

Abstract

Despite its extraordinary charge carrier mobility, the lack of an electronic bandgap in graphene limits its utilization in electronic devices. To overcome this issue, researchers have attempted to chemically modify the pristine graphene lattice in order to engineer its electronic bandstructure. While significant progress has been achieved, aggressive chemistries are often employed which are difficult to pattern and control. In an effort to overcome this issue, here we utilize the well-defined van der Waals interface between crystalline Ge(110) and epitaxial graphene to template covalent chemistry. In particular, by annealing atomically pristine graphene-germanium interfaces synthesized by chemical vapor deposition under ultra-high vacuum conditions, chemical bonding is driven between the germanium surface and the graphene lattice. The resulting bonds act as charge scattering centers that are identified by scanning tunneling microscopy. The generation of atomic-scale defects is independently confirmed by Raman spectroscopy, revealing significant densities within the graphene lattice. The resulting chemically modified graphene has the potential to impact next-generation nanoelectronic applications.