Catalytic growth mechanism and catalyst effects on electron field emission of nitrogenated carbon nanorods formed by plasma-enhanced hot filament chemical vapor deposition

Nitrogenated carbon nanorods (NCNRs) with different structures were catalytically synthesized on the silicon substrate deposited with gold films in a plasma-enhanced hot filament chemical vapor deposition system, where methane, nitrogen and hydrogen were used as the reactive gases. The structure and composition of synthesized NCNRs were investigated by field emission scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy, respectively. The results indicate that the gold particles locate at the tops of NCNRs composed of amorphous carbon with nitrogen incorporation and their growth was improved with the increase of nitrogen. According to the theory related to thermodynamics, the catalytic growth mechanism of NCNRs was studied. The electron field emission (EFE) properties of NCNRs were studied in a high-vacuum system of ∼10^-6 Pa. The EFE results show that the turn-on field changes from 2.26 to 3.11 V/μm for the NCNRs with different structures and the current density is up to about 2.2 mA/cm². The EFE results also indicate that the Fowler-Nordheim curves of NCNRs are composed of three straight lines, which are different from the F-N curve of single carbon nanorod reported. In addition, the work function of carbon nanorods was measured by X-ray photoelectron spectroscopy and the results show that the work function is closely correlated with the structure and composition of the synthesized carbon nanorods. Depending on the interface barrier formed between the NCNRs and gold particles, the effects of catalyst on the EFE properties of NCNRs were studied according to the analysis of the change in the slope of F-N curves. These results can enrich our knowledge on the structure and EFE properties of carbon nanomaterials and are highly relevant to fabrication of next generation of optoelectronic devices.