Designing of a carbon nano-structure for a high quality electron emitter

Carbon materials, including carbon nano-tube (CNT), diamond, and other carbon relatives, have received considerable attention as good materials for an electron emitter. One of the reasons is that diamond exhibits a very unique physical property known as NEA (negative electron affinity). Another practical reason is that our society requires FPDs (flat-panel-displays), such as LCDs (liquid-crystal-displays), PDPs (plasma-display-panels) and others, in order to replace the traditional display by CRT (cathode-ray-tube). In this respect, if a high-quality electron emitter is available, it can contribute greatly to the above requirement for FPDs. Because LCDs need a large area and bright back-light using the emitter, it is possible to produce FEDs (field-emission displays) as the SAMSUNG company does. The present author and his coworkers have long been trying to fabricate a good electron emitter from carbon nano-materials, and, at present, the emitter has shown a world-class property: a very low turn-on voltage (0.5 V/μm to induce a 10 μA/cm² emission current) to emit a 1 μÁ/cm² current at 1.1 V/μm and a 100 μA/cm² current at slightly lower than 4 V/μm with a gap distance of 1 mm. In this invited talk, starting from a stratagem of designing the carbon nano-structure for a good emitter on the basis of the theory of electron emission, we will give explanations on how the emitter was fabricated and on how well the emitter produces light of about 70 lm/watt with brightness of 10⁵ cd/m² (white-light) to be applied for the fabrication of mercury-free lights and white back-lights for LCDs.