Electron field emission and structural properties of carbon chemically vapor-deposited films

Low-voltage electron field emission was obtained for carbon films grown by the chemical vapor deposition (CVD) method in hydrogen-methane plasma activated by a d.c. discharge. We found that the electron field emission properties were improved by increasing the density of structural defects and non-diamond carbon inclusions in polycrystalline diamond films and, for the first time, we found that completely non-diamond CVD carbon films displayed the best field emission characteristics. The threshold electric field for the completely non-diamond CVD carbon film cathodes was as low as 1.5 V mu m(-1), the emission current reached 1 mA cm(-2), and the emission site density exceeded 10(6) cm(-2) at the field of 4 V mu m(-1). Based on RHEED, HRTEM, Raman and cathodoluminescent data of CVD films grown on silicon substrates at various methane percentages in the gas mixture, we propose a general mechanism for cold electron emission from materials containing graphite-like carbon. (C) 1999 Elsevier Science S.A. All rights reserved.