A bandgap cascade cold cathode is obtained by constructing a wide bandgap Si/C superlattice thin film; depositing Si on the epitaxial silicon surface under CVD or ALD; depositing on the Si/C surface a first metal effective to form a metal-silicide electrode; etching away the silicon substrate to form an effectively smooth Si/C surface thereon; coating the effectively smooth Si/C surface with a thicker second effective metal to form a Schottky electrode surface on which a layer of about 200 nm Pt or Au is coated with edges masked off and welded onto a Cu electrode disc as a heat sink. During avalanche multiplication under reverse bias over the Si/C layer, the bandgap energy cascades from the Schottky electrode to the sink electrode and is used to balance against the work function of the sink electrode, thereby allowing the sink electrode to function as a cold cathode emitter at a reduced applied external field.