A model of field emission from carbon nanotubes decorated by nanodiamonds

Field Emission properties of aligned bundles of SWCNTs decorated by nanodiamond grains have been experimentally studied. Additional information, required to give a physical interpretation to the experimental data, have been acquired by comparing the FE properties of such hybrid materials with those of two types of Single-Walled Carbon Nanotube (SWCNT) samples, constituted by bundles aligned and not aligned along the cathode-anode direction, respectively. For all samples, the characteristics of Field Emission have been described in the frame of the Fowler-Nordheim relationship and analysed following different models. The obtained values of current density from samples formed by SWCNT ensembles suggest that the observations are best accounted by a model based on the mechanism involving field concentration near a nanotube (that is the model generally accepted for SWCNTs and using the β factor). Conversely, if nanodiamond grains decorate the SWCNT bundles, one has to invoke a more complex two-factor model, where the β factor is coupled to another emission mechanism. Two versions of emission model are here considered: (1) the model coupling the β factor to the thermoelectric effect and; (2) the model coupling the β factor to a pre-breakdown process.