The role of dc current limitations in Fowler-Nordheim electron emission from carbon films

We investigated the electron field emission characteristics of carbon films deposited by filtered cathodic vacuum arc. A special sandwich structure wa s created using alternating layers of carbon and aluminum. This structure a llows both field emission and dc current-voltage characteristics to be meas ured on the same film. The emission current was found to follow the Fowler- Nordheim law below a critical field, E-cri. Above E-cri, the current deviat es from the Fowler-Nordheim law but follows the dc current-voltage characte ristics of the film. It is concluded that the frequently observed deviation of electron emission from the Fowler-Nordheim law at high field is due to the current limitation of the resistive carbon film. The important implicat ion of this finding for device fabrication is discussed. (C) 2000 American Institute of Physics. [S0003-6951(00)00638-0].