CNX (Carbon‐Nano‐eXit): a unique carbon‐nano‐structure to be employed for excellent electron‐emitters

Abstract

Carbon materials including Carbon‐Nano‐Tubes (CNT), Nano‐Diamonds and other Nano‐Carbon‐relatives (such as Carbon‐Nano‐Walls [CNW]) have received intense attention as good candidates for electron‐emitters. The present authors and co‐workers have long been trying to fabricate good electron‐emitters, employing a variety of carbon‐nano‐materials. Until some months ago, we claimed that CNW was the best structure for high emission‐capability among the carbon‐nano‐materials. However, by introduction of a unique structure into the CNW, we have recently succeeded to obviously improve the capability of the emitter while achieving and far shorter fabrication or deposition times. The unique structure has been named Carbon‐Nano‐eXit (CNX) and patented. The introduction of this CNX into the CNW structure can be done by some modification of plasma parameters during emitter fabrication or deposition by plasma CVD process. Now the emitter has shown a world‐top‐ranking property: very low turn‐on‐voltage (0.5 V/µm to induce 10 µA/cm2) and high emission current at low applied voltage with a gap distance of 1 mm (1 mA/cm2 current at 1.1 V/µm and 100 mA/cm2 at 2 V/µm). The emitter a is wire or pipe type emitter to avoid the so‐called “edge‐effect”. Owing to the presence of CNX which shortens the fabrication time, we are able to fabricate or deposit the emitters totally about 50∼100 km long per month by one CVD‐reactor. Then using these emitters, we are able to fabricate Mercury‐free fluorescence lamps with high efficiency (∼70 lm/watt) and a high brightness of 105 cd/m2 (white‐light). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)