Evolution of structure and morphology during plasma-enhanced chemical vapor deposition of carbon nanosheets

Abstract

The evolution of structure and morphology of carbon nanosheets during radio frequency plasma-enhanced chemical vapor deposition is investigated by X-ray diffraction (XRD) and scanning electron microscopy. Nanosheets consist of mostly vertically-aligned graphene layer stacks, 1 to > 20 layers thick, which attain approximately 5-μm lengths after 120 min of growth. XRD indicates these nanosheets contain both turbostratic and non-turbostratic graphite, and that the average thickness of nanosheets in all orientations increases with deposition time. Increases in thickness are accompanied by decreases in graphene layer spacing, a trend attributed to an increase in long-range attractive interatomic forces as more graphene layers are added. In-plane XRD scans demonstrate that preferred nanosheet orientation changes from parallel to perpendicular, relative to the substrate surface, with increasing deposition time.