Current distribution and stability of CNT´s on porous Al2O3

At present carbon nanotubes (CNT´s) are the most popular candidates for large-area cold cathode applications because of their simple fabrication and patterning techniques as well as low threshold fields for field emission (FE) which are usually below 10 V/μm. Practical cathodes with a high density of free-standing aligned CNT´s, however, suffer from non-uniform current distributions and mutual shielding effects. Moreover, pressure dependent current fluctuations and limits leading to insufficient long-term stability have been observed. In order to provide CNT´s with well-defined aspect ratio and high stability, porous Al₂O₃ templates have been considered as substrate. These might further allow the controlled growth, i.e. separation and positioning of CNT´s, by partial filling of the matrix prior to the CNT deposition. First experiments following these ideas are reported here