Integral and local field emission analyses of nanodiamond coatings for power applications

• Published in: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 1999-03, Vol.17 (2), p.670-673
• Main Authors: Göhl, A., Alimova, A. N., Habermann, T., Mescheryakova, A. L., Nau, D., Zhirnov, V. V., Müller, G.
• Format: Article
• Language: English
• ISSN: 0734-211X; 1071-1023; 1520-8567
• DOI: 10.1116/1.590615

Nanodiamond (ND) powder coatings are very promising for cold cathode applications. The suitability of a (di)electrophoretically deposited ND coating (crystallite size: 1–10 nm) for high current applications was analyzed depending on three types of Si substrates (flat, rough, Si tip array). Nondestructive direct current field emission (FE) investigations were performed by means of a field emission scanning microscope. FE properties like the electrical onset field strength E on (at 0.5 nA), current I vs E behavior, maximum current carrying ability as well as the local distribution and uniformity of emitters were analyzed by using anodes of different apex diameters D. A decrease of E on for D=10/100/1000 μm from 203/190/109 V/μm of the flat to 67/44/20 V/μm of the rough, and to ≈7/6.7/4.5 V/μm of the tip array sample is achieved by the geometrical field enhancement of the structures. The reproducible high-current density J REP >15  A/cm 2 for D=10 μm of the flat and rough sample exhibits the large potential of the ND coating for power applications. Their nonuniformity due to the μm-roughness results, however, in a low J REP for large areas. In contrast, ND coated tips showed a good uniformity over mm2 size and a moderate J REP ≈0.2  A/cm 2 , basing on about 40% of significantly emitting tips.