A non lithographic technique for the production of large area high density gridded field emission sources

We report a novel method for the production of high density arrays of gridded microtip field emission electron sources. The microporous structure of Al/sub 2/O/sub 3/, formed by anodisation of Aluminium, is exploited to provide a high density (10/sup 9/ sites cm/sup -2/) of sites for emitter fabrication without the need for individual lithographic patterning of each emitter. The small size of the resultant emitters enables operation with only moderate extraction voltage (20-50 V). Tests of groups of /spl ap/400,000 emitters have demonstrated emission current densities suitable for display applications.