UV Generation in Microcavity Plasma Devices with Encapsulated A12O3/Al Electrodes

Summary form only given. The efficient generation of ultraviolet in microscopic spatial scale is becoming significant as a key technology in applications such as displays, microchemical reactors and biomedical diagnosis or treatment. The microcavity plasma device is one promising candidate for miniaturized UV sources having high luminance and stability. In particular, we have recently observed that the extraordinary specific power loadings afforded by these devices in nanoliters volumes allow for stable glow discharge to be produced in a wide variety of gases and vapors including air at atmospheric pressure. In this presentation, we report the fabrication and performance of microdischarge arrays having electrodes encapsulated by a nanoporous dielectric. The device is a multilayer structure comprising Al foil electrodes and nanoporous Al₂O₃ as the dielectric. Having microcavities with diameters of 100-200 mum, these devices are excited by AC and generate uniform, spatially uniform glow discharges in Ar/N₂ gas mixtures at total pressures of 400-800 torr. A 3times3 array of microdischarge devices, each having a microcavity diameter of 100-200 mum dia., also produce stable glow discharges for operating voltages (peak-to-peak) in the range of 800-1200 V at 400 torr of total pressure. In this voltage range, the array exhibits a linear increase in the plasma differential resistance and the total UV output intensities increases beyond several mW-cm^-2