Microcavity-enhanced electron emission from lead zirconate-titanate cathodes

Enhanced electron emission has been observed from lead zirconate- titanate (PZT) surfaces into which arrays of microcavities have been fabricated by nanopowder blasting. Arrays of microcavities, each having an elliptical cross-sectional geometry with major and minor axis lengths of 800 and 600 ??m, respectively, and depths adjustable from 40 to 300 ??m, exhibit a pronounced dependence of the emitter electron current on microcavity depth. For electric field strengths at the emitter surface of ~5-12 V/??m, the RMS current density generated by an array of 250 ??m-deep microcavities with a packing density of 214 + 2 cm^-2 ranges from ~3 mA cm^-2 to beyond 8 mA cm^-2, or more than a factor of five larger than that produced from a planar PZT surface.