Field emission properties of carbon nanotube arrays grown in porous anodic alumina

Carbon nanotubes (CNTs), with their excellent electronic properties and extremely high aspect ratio, represent an ideal material for building electron sources based on field emission. Fowler-Nordheim equation describes quite successfully the field emission phenomenon, especially for single or isolated tips. However, some complications arise when populations of CNTs are considered, where collective effects and large variability in the emitters features influence the measured I V characteristics. In this work, the emission properties of multi-walled CNTs grown within ordered anodic alumina templates are investigated. These CNT matrices produce current densities up to some tens of mA/cm(2), and the field enhancement factor for collective emission sources can be estimated. Such material can be modelled as an ordered and uniform array of emitters and a simulation of the electrostatic field on the emission tips can be done in order to evaluate the field enhancement factor and its dependence on various geometries. This allows comparing predictions from simulation and experimental measurements, in a direct way. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim