Focusing field emission arrays constructed by self-aligned photolithography

In this article, fabrication and characterization data for a focusing Mo field emission array (FEA) are presented. This FEA is made by a technique of self-aligned photolithography. The final structure is referred to as a double-gate field emission array, with the gates acting as extraction and focusing electrodes. With this technique of self-aligned photolithography, the extraction gate aperture and the focusing gate aperture are both kept absolutely coaxial with their corresponding tips, and the ratio between diameters of the extraction aperture and the focusing aperture is kept controllable. A scanning electron microscope image of the completed microstructure shows the diameter of the extraction aperture to be as small as 1.2 μm, and the ratio of the focusing aperture diameter to that of the extraction aperture to be approximately 2:1.