| || Carbon Nanotube-based Cold Cathode for High Power Microwave Vacuum Electronic Devices: A Potential Field Emitter
Author : Verma, P.;Gautam, S.;Pal, S.;Kumar, P.;Chaturvedi, P.;Rawat, J.S.B.S.;Chaudhary, P.K.;Harsh;Basu, P.K.;Bhatanagar, P.K.
Source : Defence Science Journal ; Vol:58(5) ; 2008 ; pp 650-654
Keywords : Carbon nanotubes;Microwwave vacuum electronic devices;Cold cathode;Field emission
Abstract : Carbon nanotubes (CNTs) can be grown in the form of small, sharp spikes capable of carrying very high current densities which suggest great potential application of CNTs as cold cathode in high power microwave vacuum device applications. These cold cathode vacuum microwave devices are expected to be ideally suited for air-borne and space applications. This paper reports the initial efforts made in the development of cold cathode using PECVD grown vertically-aligned matrix of CNTs with uniform height and optimum tip density on silicon substrate. The high aspect ratio (of the order of 10,000) and novel electrical, mechanical, and thermal properties of the CNT are found to be very attractive characteristics for emission of large and stable current densities at reasonably low field. The field emission current voltage characteristics of a typical cathode gave emission current density in excess of 35 mA/cm2 at reasonably low field. The emission current in most of the samples is found to be stable over long period of time but is greatly effected by the vacuum condition during measurement. The initial measured data suggests great promise for achieving high current densities at practical electric fields.