| Summary: | 博士 === 逢甲大學 === 電機與通訊工程博士學位學程 === 103 === Abstract (in English)
The DC magnetron sputtering system was used to fabricate Co precursors. Co thin films were grown on the glass substrates and cleaned in an ultrasonic cleaner with alcohol for 15 minutes, and then rinsed with distilled water.600 nm Co films were formed on the substrate at a deposition rate of 10 nm/minute. And the fabricated samples were put in the furnace at different temperature and times with Selenization、oxidation、Sulfurization by Cobalt.
In the selenization of Co, this work investigates a simple and non-toxic method to transform pre-deposited amorphous Co film into CoSe2 thin films by sputtering the Co film onto glass substrates, which are then heated at a fixed, low temperature of 300 °C. Single CoSe2-phase films having good crystallinity were obtained at a selenisation time ≧ 24 hours. At a selenisation time of 72 hours, a novel layered nanostructure CoSe2 having two different nano-morphological layers was observed. Optical analyses of the CoSe2 films obtained at 72 hours enabled us to deduct a large absorption of α > 1.0 × 105 cm-1 and a direct band gap of 1.51 eV.
At temperatures of 400 and 500 °C, the Co films have a crystalline nanostructure with bilayered topography. The Hall effect and electrical measurement of the CoSe2 films heated to 500 °C show p-type metallic behavior. Optical analyses of the CoSe2 films at 500 °C show a large absorption and a direct band gap (~ 1.0 eV). Nano-porous crystallite CoSe2 film selenized at 500 °C is a p-type metallic compound with a suitable band gap and high absorption coefficient, which makes them quite useful as a new candidate for solar energy photo-electrode materials.
In the oxidation of Co, large area and uniform nanosheets Co3O4 have been fabricated by thermal annealing of cobalt thin film under the DC magnetron sputtering method. The synthesis is based on controlling the simple thermal oxidative formation of precursor Co films. The Co films were heated at 300, 400, and 500 °C for two hours in a pure oxygen atmosphere. At the 300 °C, CoO and Co3O4, phases appear to survive together. An amount of pure polycrystalline Co3O4 nanosheets were observed at 400 °C. The structural and morphological properties of the nanosheets Co3O4 were characterized by means of transmission electron microscopy (TEM) and Raman spectroscopy.
Keywords : DC magnetron sputtering method、CoSe2、Co3O4 、CoS2、nanosheet
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