Field Emission and Nanostructure of Carbon Films

ABSTRACTThe results of field emission measurements of various forms of carbon films are reported. It is shown that the films' nanostructure is a crucial factor determining the field emission properties. In particular, smooth, pulsed-laser deposited amorphous carbon films with both high and low sp3 contents are poor field emitters. This is similar to the results obtained for smooth nanocrystalline, sp2 - bonded carbon films. In contrast, carbon films prepared by hot-filament chemical vapor deposition (HF-CVD) exhibit very good field emission properties, including low emission turn-on fields, high emission site density, and excellent durability. HF-CVD carbon films were found to be predominantly sp2 -bonded. However, surface morphology studies show that these films are thoroughly nanostructured, which is believed to be responsible for their promising field emission properties.