Surface characterization of low energy Si ion implanted graphene

Heteroatom doping is a critical route to implement graphene-based applications. Ion implantation is an ideal method for its advantages of controllability and diversity, but limited in two-dimensional materials applications by the lack of dopants with appropriate energy. In this work, single-layer graphene is implanted with sputtered Si atoms, which are from a pure silicon target bombarded with 15 keV Ar ions. Si atoms are doped into graphene with concentration up to 8.9 at%, which can be accurately controlled by adjusting the ion fluence. The Raman spectra manifests that the irradiation damage of graphene are mainly substitutions and adsorptions, while the vacancies maintain in a low level. In addition, the work function of the doped graphene increases from 4.34 to 4.46 eV when the Si concentration varied from zero to 8.9 at%, showing promising potential in regulating the performance of related electrical applications. Our work provides a simple, controllable, and widely applicable approach for doping two-dimensional materials with nearly all the elements besides silicon.