Laminar composite lateral field-emission cathode and fabrica tion process

摘要

A lateral-emitter electron field emission device (10) includes a thin-film laminar composite emitter structure (50) including two or more films (70, 80, 90) composed of materials having different etch rates. The simplest emitter consists of two ultra-thin layers (70 and 80 or 90) etched differentially so that a salient remaining portion of the more etch-resistant layer (70) protrudes beyond the less etch-resistant layer (80 or 90) to form a small-radius tip (100). Preferably, the most etch-resistant layer (70) is N-doped diamond which has a nearly zero work function. The emitter structure may be a three-layer structure with upper and/or lower layers (80, 90) acting as a physical supporting and integral electrical conducting medium. In a preferred process for fabricating the device, the laminar composite emitter (50) is first patterned by a directional trench etch. During or after fabrication of the trench (140), the laminar composite emitter (50) is differentially etched as described above by chemical or electro-chemical etch, differential electropolishing, or differential ablation, leaving a protruding ultra-thin emitter tip (100).