Vertically aligned nitrogen-doped nanocrystalline diamond nanorods are fabricated from nitrogen-doped nanocrystalline diamond films using reactive ion etching in oxygen plasma. These nanorods show enhanced thermionic electron emission (TEE) characteristics, viz., a high current density of 12.0 mA/cm2 and a work function value of 4.5 eV with an applied voltage of 3 V at 923 K. The enhanced TEE characteristics of these nanorods are ascribed to the induction of nanographitic phases at the grain boundaries and the field penetration effect through the local field enhancement from nanorods owing to a high aspect ratio and an excellent field enhancement factor.
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The authors thank the financial support of the Research Foundation Flanders (FWO) via Research Grant 12I8416N and Research Project 1519817N, and the Methusalem "NANO" network. The Hercules Foundation Flanders is acknowledged for financial support of the Raman equipment. The Qu-Ant-EM microscope used for the TEM experiments was partly funded by the Hercules fund from the Flemish Government. S.K. and J.V. acknowledge funding from GOA project “Solarpaint” of the University of Antwerp. K.J. Sankaran and P. Pobedinskas are Postdoctoral Fellows of FWO.
The supplementary material for this article can be found at https://doi.org/10.1557/mrc.2018.158
K.J.S., K.H., and I.N. Lin conceived and designed the experiments, synthesized the samples and wrote the manuscript with inputs from all the co-authors. S.D., P.P., and M.K.V.B. performed the SEM and Raman spectroscopy measurements. S.D. and S.S.R. performed the KPFM imaging experiments. S.K., J.V., C.J.Y., and K.C.L. performed the electron microscopic imaging and EEL spectroscopy measurements. J.P.T. and K.T.L. performed the XPS measurements.
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Sankaran, K.J., Deshmukh, S., Korneychuk, S. et al. Fabrication, microstructure, and enhanced thermionic electron emission properties of vertically aligned nitrogen-doped nanocrystalline diamond nanorods. MRS Communications 8, 1311–1320 (2018). https://doi.org/10.1557/mrc.2018.158