https://doi.org/10.1051/epjap/2012110473
Copper nanocones grown in polymer ion-track membranes as field emitters
1
FB C Physics Department, University of Wuppertal, 42097 Wuppertal, Germany
2
Materials Research, GSI Helmholtz Centre for Heavy Ion Research, 64291 Darmstadt, Germany
a e-mail: serbun@physik.uni-wuppertal.de
Received:
16
December
2011
Revised:
23
February
2012
Accepted:
29
February
2012
Published online:
23
March
2012
Field emission (FE) properties of unstructured and patch-structured cathodes with randomly distributed and vertically aligned copper nanocones (Cu-NCs) are reported. The cones of ~28 μm height, 2.4 μm base diameter and 95–220 nm tip radius were fabricated by electrochemical deposition of Cu into conical channels of heavy-ion-irradiated and asymmetrically etched polycarbonate membranes. FE measurements of the unstructured cathodes with slowly-grown Cu-NCs of high number density (107 cm−2) and excellent mechanical stability yield stable currents up to 280 μA from an emission spot of 30 μm. For the structured cathodes with a triangular patch array of less dense Cu-NCs (<106 cm−2), well-aligned FE with ~90% efficiency is reproducibly achieved. A trade-off between low onset field (~22 V/μm) for sparsely grown Cu-NCs with sharp tips and high current limit (~100 μA) for densely grown ones with broader tips is observed. Possibilities for further optimization of such field emitters for cold cathode applications are discussed.
© EDP Sciences, 2012
