Growth And Field Emission Properties Of Nanotip Arrays Of Amorphous Carbon With Embedded Hexagonal Diamond Nanoparticles

Field emission displays (FED) combine the advantages of cathode ray tube (CRT) with the packaging advantages of other flat panel technologies, namely their high brightness, high contrast levels, very fast response times and low power. The urgent challenge is to develop field emission cathode materials with less power and long lifetime. Amorphous carbon nanotip arrays as cathode materials of FED deposited by magnetic filtered cathodic arc plasma (FCAP) technology combined with funnel-shaped opening anodic aluminum oxide (AAO) template. The microstructure of amorphous carbon nanotip arrays was characterized. The results show that hexagonal diamond nanoparticles were formed in the amorphous carbon matrix. The effect of the microstructure on the field emission properties of the amorphous carbon nanotip arrays was investigated. The formation mechanism of hexagonal diamond nanoparticles was also discussed. The main contents of this thesis are as follows:1. Compared to other displays, the advantages of FED in the applications were presented. The improvements of carbon-based materials on the field emission properties were introduced. The deposition technologies to prepared carbon-based materials were also introduced. The preparation methods and field emission properties of quasi-one dimensional materials were described in detail. The unique field emission properties of as-fabricated amorphous carbon nanotip arrays make it good candidate as cathode materials in the flat panel displays.2. Highly ordered nanotip arrays of amorphous carbon with embedded hexagonal diamond nanoparticles were prepared at room temperature for use as excellent field emitters by a unique combination of AAO template and FCAP technology. The nanotips were about 100nm in width at the bottom and 150 nm in height with density up to 1010 cm-2. Transmission electron microscopy investigation indicates that many nanoparticles with diameters of about 10 nm were embedded in the amorphous carbon matrix, which was proved to be hexagonal diamond phase by Raman spectrum and selected-area electron diffraction. The nanotip arrays with hexagonal diamond phase exhibit a low turn-on field of 0.5 V/um and a threshold field of 3.5 V/μm at 10 mA/cm2, the emission current is very stable. There is no previous literature report on the field emission properties of hexagonal diamond and its preparation at room temperature under high-vacuum condition. The effect of the microstructure on the field emission properties of the amorphous carbon nanotip arrays was investigated. The formation mechanism of hexagonal diamond nanoparticles was also discussed.3. The electrical field has a strong shield effect at high tip density due to the interaction of the electrostatic fields. The shield effect decreases the density of effective emission sites. By changing the anode oxidized electrolyte and adjusting the voltage, AAO templates with different inter pore distances between 100 to 800 nm were prepared in this work, which is of great significance in preparing low-density tip arrays.