Large current carbon nanotube emitter growth using nickel as a buffer layer

A method is reported for the fabrication of vertically aligned carbon nanotube emitter arrays by microwave plasma chemical vapour deposition. The technique uses a catalyst structure in which Fe, Ni and Al, respectively, acted as the catalyst for carbon nanotube growth, a buffer layer and an isolated layer between the Fe and Ni layers. The nanotubes were suitable for large current field emission applications. SEM images showed that the length and the diameter of the CNTs were uniform. Accordingly the CNT emitter arrays presented excellent height uniformity. Furthermore, the adhesion of the CNTs to the substrate was stable, and the electrical conductance between the CNTs and the substrate was good enough to ensure the continual emission of plenty of electrons. A highly stable field emission current density of more than 2?A?cm?2 with a total field emission current of 20?mA was obtained. These results indicate a fabrication route for greatly improving the field emission characteristics of CNT-based field emitter arrays.