Abstract
Beam focusing is a crucial technique for promoting the resolution of the field-emission displays. Various focusing structures for the Spindt-type field emission device have been proposed and applied on previous works, e.g. coaxial-type focusing, coplanar-type focusing, ridge-type focusing, and mesh-electrode focusing. The diamond-film coating provides another possibility to design new types of field emission devices with inherently smaller beam size. The planar-type and concave-lens-type cathodes are examples. In this study, diamond-film-coated field emitters with different emitting shapes are proposed and simulated by the MAGIC particle-in-cell code. The focusing effect inherent in the emitting shape will be characterized and analyzed. The traditional Spindt-type devices with various focusing structures are also studied for comparisons. The electron trajectories, the spot sizes of beams, and I-V curves are investigated systematically for each device.