Field emission proporties of copper nanocones grown in polymer ion-track mem branes

Copper nanocones (Cu-NCs) of about 30 mu m length and of similar to 2.4 mu m in base and similar to 380 nm in tip diameter were grown in polymer ion-track membranes. Field emission (FE) properties of two types of cathodes with randomly distributed Cu-NCs were investigated. The unstructured cathode with high number density (10(7) cm(-2)) and excellent mechanical stability of Cu-NCs yielded stable currents up to 100 mu A at electric fields of about 100 V/mu m as measured with an anode of 30 mu m in diameter. The structured cathode with triangular patch array of less Cu-NCs (< 10(6) cm(-2)) provided well-aligned FE with about 90 % efficiency at much reduced onset field levels (similar to 20 V/mu m) but lower current limits, too. SEM images of the random Cu-NCs after current processing revealed only slight changes of the tip morphology. The actual status and further optimization steps of structured Cu-NC cathodes for device applications will be discussed.