Local probing of the field emission stability of vertically aligned multi-walled carbon nanotubes

Metallic cantilever in high vacuum atomic force microscope has been used as anode for field emission experiments from densely packed vertically aligned multi-walled carbon nanotubes. The high spatial resolution provided by the scanning probe technique allowed precise setting of the tip-sample distance in the submicron region. The dimension of the probe (curvature radius below 50 nm) allowed to measure current contribution from sample areas smaller than 1 μm². The study of long-term stability evidenced that on these small areas the field emission current remains stable (within 10% fluctuations) several hours (at least up to 72 h) at current intensities between 10⁻⁵ and 10⁻⁸ A. Improvement of the current stability has been observed after performing long-time conditioning process to remove possible adsorbates on the nanotubes.