Field emission of nitrogenated amorphous carbon films

Field emitter films based on nitrogenated amorphous carbon (a-C:N) were dep osited on different chromium patterns on glass by sputtering of graphite em ploying an electron cyclotron resonance plasma as argon and nitrogen ion so urce. The a-C:N films contain between 0.6 and 21 at.% nitrogen. All films h ave a low resistivity (<0.1 Omega cm) and a microhardness of about 15 GPa i ndicating a high content of sp(2) bonds. The vacuum electronic properties o f the films were checked in an UHV chamber in a plane to plane set-up. To l ocalize the emission sites the excitation of a low voltage phosphor (ZnO:Zn ) was monitored by a CCD camera. After an activation by vacuum are discharg es emission of electrons occurred at macroscopic electrical fields au low a s 3.2 V/mu m. The discharges generate delaminated a-C:N film fragments that bear the FE current due to field enhancement. Discharge and therefore FE o nly took place at the edges of the emitter stripes due to a macroscopic fie ld enhancement. Two kinds of activation were found leading to different mic rostructures of the emitter and different FE chatacreristic. The influence of substrate bias, nitrogen content, film thickness and emitter geometry on the field emission was also surveyed. (C) 1999 Elsevier Science Ltd. All r ights reserved.