| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
This work has three purposes. First purpose was to control the morphology of nano-sized ZnO. Second purpose was to develop ZnO nano-rod suitable for field emission cathode. Third purpose, which is a novel application of ZnO nano-rod, was to lower the operation voltage of an inorganic electroluminescent device by using ZnO nano-rod. Nano-sized ZnO was grown by chemical vapor deposition method combined with laser ablation. For the first purpose, the effects of growth conditions on the morphology of nano-sized ZnO have been investigated. It was found that the type of laser ablation target remarkably influences the morphology of nano-sized ZnO, and using Mn and sintered ZnO among W, Co, Mn, Er, Al sintered ZnO as a laser ablation target easily lead to nano-rod shaped ZnO vertically grown on the substrate. Laser ablation time and O_2 flow rate could control the diameter of ZnO nano-rod. When rod diameter became small, the growth direction of rod was randomly-oriented. For the second purpose
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, the vertically-oriented ZnO nano-rods with small diameter were obtained by two step growth processes. Firstly, the vertically-oriented ZnO nano-rods with thick diameter ranged from 80 to 120 nm were grown with O_2 flow rate of 1.5 SCCM. Subsequent CVD growth with O_2 flow rate below 0.6 SCCM provided ZnO nano-rods with thin diameter ranged from 35 to 53 nm on the center of first-step nano-rods. A field emission current of ZnO nano-rods by two step growth processes was increased by two orders of magnitude at an electric field of 30 V/μm. For the third purpose, AC type and DC type inorganic thin film electroluminescent devices using ZnO nano-rods layer adjacent to an EL active layer as an intermediate layer were fabricated. The luminance-voltage characteristics of the ACEL device were very sensitive to properties of a ZnO nano-rods layer. With an as-deposited ZnO nano-rods layer, the operation voltage was reduced below the luminance region about 15% less than the saturation luminance for the device without a ZnO nano-rods layer. Especially, the threshold voltage of the ACEL device using an as-deposited ZnO nano-rods layer was reduced by about 40.1 %. Less
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