2, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
The dopants in graphene (like Si, P, and N) is found to be dynamically mobile, where the atom can travel through the lattice by exchanging sites with the neighbor C atom. Here, we investigate on the machism of lattice hopping through low voltage (60keV) aberration corrected scanning transmission electron microscope (AC-STEM), and we find that the basic machanism is categorized into two types: out-of-plane exchange, and in-plane exchange. Details of the machanism is further studied by density functional theory (DFT), comparing the energy barrier of transition state for different atom species through nudged elastic band (NEB) theory. This fundamental study of lattice dynamics of dopant atoms will pave the way for further investigation on engineering the configuration of dopant atoms in graphene.