We investigate experimentally the transport properties of single-walled carbon nanotube bundles as a function of temperature and applied current over broad intervals of these variables. The analysis is performed on arrays of nanotube bundles whose axes are aligned along the direction of the externally supplied bias current. The data are found consistent with a charge transport model governed by the tunneling between metallic regions occurring through potential barriers generated by a nanotube’s contact areas or bundle surfaces. Based on this model and on experimental data, we describe quantitatively the dependencies of the height of these barriers upon bias current and temperature.

Efficient and robust cold cathodes have been assembled using as emitting material mats of single wall carbon nanotubes (SWCNTs) coated with nanodiamonds. The preparation of the hybrid nanotube/nanodiamond structures by chemical vapor deposition is a route suitable to be scaled up and adapted to the electronic industry requirements. Turn-on field of 1.7 V/μm and emission current density J of 6 mA/cm2 at applied field E of 6.2 V/μm were measured. The field emission properties of SWCNT coated with nanodiamond are very attractive in terms of reproducibility, current stability under medium vacuum and lack of arcing. Moreover, the diamond coating acts against the adsorption of chemical species, making it possible to avoid the outgassing procedures usually needed for current stabilization and allowing to reduce the time response for electron sources assembled with these hybrid materials.