Direct graphene synthesis on Si(1 0 0) by inductively coupled plasma beam source

Abstract

The graphene was synthesized directly on the Si(100) substrate by an Inductively Coupled Plasma Beam Source without any catalyst. Plasma power, methane gas flow, hydrogen gas flow, temperature and time effects on graphene layers number and flake size, defects density, and surface morphology were studied. Prevailing defects type was considered. Boundary defects dominated in most samples due to the polycrystalline nature of the directly synthesized graphene. However, high methane gas flows, low synthesis times, and low synthesis temperatures were beneficial for the hydrogenation of the growing graphene. On-site defects prevailed in these samples. It was found that synthesis power, temperature, and time should be optimized to avoid out-of-plane graphene growth. An additional hydrogen gas flow effectively controlled graphene layers number. D + D‘ and D + D“ peaks were explored. It was supposed that the D + D‘ peak is mainly related to the on-site defects associated with a hydrogen atom bonded to the carbon atom in the graphene sheet. The line-of-sight graphene deposition was demonstrated. The main graphene growth-related physical and chemical processes were considered. The observed results were explained by a competition between graphene growth, hydrogen etching, hydrogenation, and thermal stress release.