Using a self-structured thin-film edge emitter to improve the field emission from tetrahedral amorphous carbon

Field emission from tetrahedral amorphous carbon (ta-C) films prepared by vacuum arc deposition methods has been observed previously and attempts to fabricate a gated microelectronic cathode using this material are reported here. Field emission was obtained when the gate was biased at 12 V d.c. However, the emission site density is inhomogeneous. Further investigation has led us to conclude that field emission originated from graphite inclusions randomly distributed within the ta-C film caused by local field enhancement. It is thus difficult to control the position of these emission sites and to achieve the uniformity and site density required for field emission display applications. An alternative approach is therefore reported in this paper. A self-structured thin-film edge emitter was fabricated in which the edge of the ta-C film provided a local field enhancement site. Thus, it was possible to control the position and density of the emission sites precisely by patterning the film edges. High emission site density was successfully obtained from a 125 by 100 array of emitters over an area of 1 cm2.