Plasma enhanced vapour deposition grown cold cathode emits high current density

• Published in: Indian journal of pure & applied physics 2007-11, Vol.45 (11), p.906-909
• Main Authors: Kumar, P, Pal, S, Gautam, S, Chaturvedi, P, Verma, P, Rawat, JSBS, Harsh, JSBS, Ghosal, P, Bhatnagar, P K
• Format: Article
• Language: English
• ISSN: 0019-5596

The high aspect ratio of the carbon nanotube (CNT) (of the order of 10,000) coupled with novel electrical, mechanical and thermal properties of the CNT make them very attractive candidate for cold cathode application in high power vacuum devices. Such CNT based cold cathode (CCC) can provide large and stable emission current densities at reasonably low field and can be switched on and off instantaneously with no limitation on grid modulation. These CCC based vacuum devices can also be efficiently operated under harsh ambient conditions and therefore, ideally suited for air borne and space applications. In this paper, the development of CCC using vertically aligned matrix of carbon nanotubes with optimum tip density grown by chemical vapour deposition (CVD) and plasma enhanced vapour deposition (PECVD) technique on silicon substrate has been reported. The field emission characteristics of a typical CCC grown via CVD and PECVD were compared. The field emission current density obtained in case of CVD sample was 8 mA/cm2 at a field of 3.6 V/?m while it was 35 mA/cm2 at the same field in case of PECVD grown CCC. The emission current in most of the samples was found to be stable over long period of time. Our measurements suggest great promise for achieving high current densities at practical electric fields.