VACUUM-ARC DISCHARGES PRECEDING HIGH ELECTRON FIELD-EMISSION FROM CARBON-FILMS

Field emission measurements on chemical vapor deposition diamond and l aser ablated a-C films show an activation step after reaching a certai n critical electric field. At this field a vacuum are of some hundred as duration initiates. While high current arcing leads to the evaporat ion of the spot surface melting, amorphization or cracking of the film is encountered for lower currents. In any case, much higher electron emission can be observed after this activation procedure due possibly to tip formation resulting in an electric field enhancement. By using a 1 G Ohm resistance the discharge current can be limited nevertheless , an activation is observed. (C) 1996 American Institute of Physics.