FIELD EMISSION FROM A NEW TYPE OF ELECTRON SOURCE

A new type of field emission electron source has been developed. In this paper, the construction, characteristics and behaviour of tungsten micropoint emitters coated with a sub-micron layer of hydrocarbon using a TEM with poor (~ 10-3 torr) vacuum conditions are described. The hydrocarbon coating has been verified using the X-Ray energy dispersive analysis technique of a SEM. The technical capabilities and potential of the new type of electron source are compared with those of other comparable composite micropoint field emitters and other types of electron sources currently in use. The emission properties presented here include I-V characteristics, emission images and electron energy spectra of this type of composite micropoint emitters. The effect on the behaviour and characteristics of baking the coated emitters at temperatures ranging between 140° C and 350° C is also studied. The behaviour of the emitter has been interpreted in terms of a field-induced hot-electron emission mehism associated with metal-insulsator-vacuum (M-I-V) regime