Control of cavity cross section in microplasma devices: Luminance and temporal response of 200×100 and 320×160 arrays with parabolic Al2 O3 microcavities

Intense green luminance and luminous efficacies approaching 4 lm/W have been observed for large (50×50 to 320×160) arrays of microplasma devices with parabolic cross-sectional Al2 O3 microcavities and conformal aluminum electrodes, operating in Ne/Xe gas mixtures. Precise control of the cross-sectional geometry and surface morphology of the cavities within Al/ Al2 O3 microplasma devices having a dielectric barrier structure has been achieved with a sequence of wet electrochemical processes. Continuous variation of the cavity cross section between a linear taper and parabolic geometry can be specified and all dimensions controlled to within ±2%. Aluminum electrodes encompassing each cavity are azimuthally symmetric and the inner face of each electrode is conformal to the Al2 O3 microcavity wall. Arrays comprising 20 000 devices (in a 200×100 configuration) with a parabolic microcavity wall profile and an emitting aperture 160±2 μm in diameter produce a green luminance >1800 cd/ m2 and a peak luminous efficacy of 3.9 lm/W in Ne/30% Xe gas mixtures at a total pressure of 500 Torr. Temporal response measurements show the visible emission rise time of 200-250 ns to be limited only by the rise time of the voltage waveform itself.