Interplay of current crowding and current self-quenching effects in planar cold cathodes

In planar cold cathodes making use of semimetallic thin films to achieve low or negative electron affinity, the effects of dc current crowding can be affected by the trapping of electrons being reflected towards the cathode as a result of space-charge effects in the vacuum gap between cathode and anode. A self-consistent solution of the interplay between current crowding and space-charge effects can lead to a nonmonotonic lateral distribution of the anode current density depending on the width of the emission window. This behavior is in sharp contrast with the monotonic decrease of the anode current density from the edges towards the center of the emission window when space-charge effects in the vacuum region are neglected.