An amorphous diamond material that is capable of emitting electrons in a vacuum upon the input of a sufficient amount of energy is disclosed. The material may utilize both compositional and geometrical aspects in order to maximize electron output and minimize required energy input. In one aspect, the amorphous diamond material may include at least about 90% carbon atoms with at least about 30% of such carbon atoms bonded in distorted tetrahedral coordination. Further, the material may be configured with an emission surface having an asperity height of from about 10 to about 10,000 nanometers. A variety of energy types may be used separately or in combination to facilitate electron flow, such as thermal energy, light energy, and induced electric field energy. The amorphous diamond material may be incorporated into a variety of vacuum-type devices, such as switches, laser diodes, electrical generators, and cooling devices.