Semiconducting microcavity and microchannel plasma devices

Preferred embodiments of the invention provide semiconducting microcavity plasma devices. Preferred embodiments of the invention are microcavity plasma devices having at least two pn junctions, separated by a microcavity or microchannel and powered by alternate half-cycles of a time-varying voltage waveform. Alternate embodiments have a single pn junction. Microplasma is produced throughout the cavity between single or multiple pn junctions and a dielectric layer isolates the microplasma from the single or multiple pn junctions. Additional preferred embodiments are devices in which the spatial extent of the plasma itself or the n or p regions associated with a pn junction are altered by a third (control) electrode.