Thin films of single-wall carbon nanotubes (SWNT) with various thicknesses were fabricated, and their optical andelectrical properties were investigated. The SWNTs of various thicknesses were directly coated in the arc-discharge chamberduring the synthesis and then thermally and chemically purified. The crystalline quality of the SWNTs was improved by thepurification processes as determined by Raman spectroscopy measurements. The resistance of the film is the lowest for thechemically purified SWNTs. The resistance vs. thickness measurements reveal the percolation thickness of the SWNT film tobe ~50nm. Optical absorption coefficient due to Beer-Lambert is estimated to be 7.1×10-2nm-1. The film thickness for 80%transparency is about 32nm, and the sheet resistance is 242Ω/sq. The authors also confirmed the relation between electricalconductance and optical conductance with very good reliability by measuring the resistance and transparency measurements.

Titanium dioxide thin films were fabricated as hydrogen sensors and its sensing properties were tested. The titanium was deposited on a SiO2/Si substrate by the DC magnetron sputtering method and was oxidized at an optimized temperature of 850˚C in air. The titanium film originally had smooth surface morphology, but the film agglomerated to nano-size grains when the temperature reached oxidation temperature where it formed titanium oxide with a rutile structure. The oxide thin film formed by grains of tens of nanometers size also showed many short cracks and voids between the grains. The response to 1% hydrogen gas was ~2×106 at the optimum sensing temperature of 200˚C, and ~103 at room temperature. This extremely high sensitivity of the thin film to hydrogen was due partly to the porous structure of the nano-sized sensing particles. Other sensor properties were also examined.

The hydrogen gas sensing properties of a zinc oxide nanowire structure were studied. Porous zinc oxide nanowire structures were fabricated by oxidizing zinc deposited on a single-wall carbon nanotube (SWNT) template. This revealed a porous ZnO-SWNT composite due to the porosity in the SWNT film. The gas sensing properties were compared with those of zinc oxide thin films deposited on SiO2/Si substrates in sensitivity and operating temperature. The composite structure showed higher sensitivity and lower operating temperature than the zinc oxide film. It showed a response even at room temperature while the film structure did not.

The effects of the field emission property in relation to the surface morphology and adhesion force were investigated. The single-wall-nanotube-based cathode was obtained by use of an in-situ arc discharge synthesis method, a screen-printing method and a spray method. The morphologies of the formed emitter layers were very different. The emission stability and uniformity were dramatically improved by employing an in-situ arc discharge synthesis method. In this study, it was confirmed that the current stability and uniformity of the field emission of the cathode depend on the surface morphology and adhesion force of the emitters. The current stability of the field emission device was also studied through an electrical aging process by varying the current and electric field.

A simple method to deposit carbon nanotube films uniformly on large area substrates using an arc discharge method is reported in this paper. The arc discharge method was modified to deposit carbon nanotube films in situ on the substrates. The substrates were scanned several times over the arcing point for a uniform film thickness. Deposition was carried out under variable dc bias conditions at 600 torr of H2 gas. The thickness uniformity of the single-wall carbon nanotube films as characterized by a four-point probe was within 30% deviation. The morphology and crystal quality of the single-wall carbon nanotube film were also characterized by field emission scanning electron microscopy and Raman spectroscopy.

열화학 기상 증착법을 이용하여 암모니아 처리에 따른 촉매 금속의 표면형태와 탄소 나노튜브의 성장을 조사하였다. 암모니아 처리의 열화학 과정의 조절에 의해 고르게 분산된 수직 성장된 탄소 나노튜브를 얻었다. 탄소 나노튜브 합성시 암모니아처리는 수직성장 및 고밀도 성장에 중요한 과정으로 그 역할에 대해 알아보았다. 고밀도의 수직 배향된 탄소나노튜브의 구조와 형태는 주사전자 현미경과 투과전자 현미경, 라만을 이용하여 관찰하였다.