Woon-Jo Jeong

Electrical and optical properties of ZnO thin film as a function of deposition parameters

Al-doped zinc oxide (AZO) and undoped zinc oxide (ZO) films have been prepared by rf magnetron sputtering. Films with low resistivities were achieved by using an Al-doped ZnO target and films with higher resistivities can be obtained by introducing oxygen during deposition. An AZO thin film which was fabricated with an rf power of 180W, a sputtering pressure of 10 m Torr and thickness of 5000 A showed the lowest resistivity of 1.4 x 10 -4 Ωcm and transmittance of 95% in the visible range, and ZO film made by reactive sputtering with the above 10% oxygen content had the highest resistivity of 6×10 14 Ωcm.

Photovoltaic characteristics of CuInS2CdS solar cell by electron beam evaporation

When a CuInS2CdS solar cell was fabricated by depositing CdS thin film with dopant In of 1.0 at% on ternary compound CuInS2 thin film with the lowest resistivity of 5.59 × 10−2 Ωcm, its best result was as follows: Voc = 461 mV, Isc = 26.9 mA, FF = 0.685, η = 5.66% under the illumination of 100 mW/cm2. And its series resistance and lattice mismatch was 5.1 Ω and 3.2%, respectively. Besides, a 4 layer structure solar cell of ϱ-CuInS2/high ϱ-CuInS2/high ϱ-CdS/low ϱ - CdS has been fabricated. When thickness of high ϱ - CuInS2 was 0.2 μm, its best result was as follows: Voc = 580 mV, Isc = 30.6 mA, FF = 0.697, η = 8.25%. An its series resistance and lattice mismatch were 4.3 Ω and 2.8%, respectively.

A Study on Properties of CuInSe 2 Thin Films by Substrate Temperature and Annealing Temperature

Process variables for manufacturing the thin film were established in order to clarify optimum conditions for growth of the thin film depending upon process conditions (substrate temperature, sputtering pressure, DC/RF Power), and then by changing a number of vapor deposition conditions and Annealing conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the , Cu, In and Se were vapor-deposited in the named order. Among them, Cu and In were vapor-deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1 : 1, while the surface temperature having an effect on the quality of the thin film was changed from at intervals of . The diffract fringe of X-ray, which depended upon the substrate temperature and the Annealing temperature of the manufactured thin film, was investigated. scanning electron microgaphs of represents a case that a sample manufactured at the substrate temperature of was thermally treated at . As a result, at of the Annealing temperature, their chemical composition was measured in the proportion of 1 : 1 : 2. It could be known that under this condition, the most excellent thin film was formed, compared with the other conditions.

Properties of Indium Tin Oxide Transparent Conductive Thin Films at Various Substrate and Annealing Temperature

ITO thin films with thickness of 3000 were fabricated by rf magnetron sputtering system with a 10 mol % SnO-90 mol % InOtarget at various substrate temperature and annealing temperature in air. And we investigated structural, electrical and optical characteristics of them. It`s resistivity, carrier concentration and Hall mobility was 210-4/ Ωcm, 71020/∼ 91020/ cm-3/ and 21∼23 cm/Vsec respectively. And it`s optical transmittance and energy band gap was above 85 % in the visible range and 3.53 eV respectively.

Study on Conversion of Carbon Dioxide to Methyl Alcohol over Ceramic Monolith Supported CuO and ZnO Catalysts

Methyl alcohol is one of the basic intermediates in the chemical industry and is also being used as a fuel additive and as a clean burning fuel. In this study, conversion of carbon dioxide to methyl alcohol was investigated using catalytic chemical methods. Ceramic monoliths (M) with were used as catalyst supports. Monolith-supported CuO-ZnO catalysts were prepared by wash-coat method. The prepared catalysts were characterized by using ICP analysis, TEM images and XRD patterns. The catalytic activity for carbon dioxide hydrogenation to methyl alcohol was investigated using a flow-type reactor under various reaction temperature, pressure and contact time. In the preparation of monolith-supported CuO-ZnO catalysts by wash-coat method, proper concentration of precursors solution was 25.7% (w/v). The mixed crystal of CuO and ZnO was well supported on monolith. And it was known that more CuO component may be supported than ZnO component. Conversion of carbon dioxide was increased with increasing reaction temperature, but methyl alcohol selectivity was decreased. Optimum reaction temperature was about under 20 atm because of the reverse water gas shift reaction. Maximum yield of methyl alcohol over CuO-ZnO/M catalyst was 5.1 mol% at and 20 atm.

The Properties of HfO 2 Thin Films by DC/RF Magnetron Sputtering and Thermal Evaporation Method

[ ] thin film were prepared in order to clarify optimum conditions for growth of the thin film depending upon process, and then by changing a number of deposition conditions and heat treatment conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the , Cu, In and Se were deposited in the named order. Among them, Cu and In were deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1:1, while the annealing temperature having an effect on the quality of the thin film was changed from to at intervals of .ℊ攀Ѐ㘱〻ጀ䵥摩捩湥⁡湤⁨敬慴栀

Effect of Molar Concentration of NH4OH on Photocatalytic Activity in Preparation of Nanosized TiO2 Powder from Spent Titanium Chip by Sol-Gel Method.

The TiO2 powder was prepared from the spent titanium chips by applying the sol-gel method. The spent titanium chip was dissolved in HCl solution, and then NH4OH solution was added. The molar concentration of NH4OH solution was 2 M, 4 M, 8 M, and 10 M. Obtained TiO2 powders were calcined at 200 degrees C, 400 degrees C, and 600 degrees C. The prepared TiO2 powder was characterized using a particle size analysis, BET surface area, and XRD analysis. The crystal structure of the TiO2 powder was rutile type and anatase. The highest BET surface area of TiO2 powder was 432.8 m2/g. The photocatalytic property of the TiO2 powder was evaluated as decomposition rate of methylene blue(MB) by using a liquid phase stirred reactor. UV source was a UV-A, and concentration of MB in most experiments was 8 ppm. The concentration of MB was measured by absorbance at 664 nm using UV spectroscopy. Photocatalytic efficiency of prepared TiO2 powder depended highly on concentration of NH4OH solution. The TiO2 powder prepared with 8 M-NH4OH solution showed the highest efficiency, the decomposition efficiency at decomposition time of 2 hr and MB concentration of pH 8 was 98%.

Catalytic Activity of Nanosized CuO-ZnO Supported on Titanium Chips in Hydrogenation of Carbon Dioxide to Methyl Alcohol.

In this study, titanium chips (TC) generated from industrial facilities was utilized as TiO2 support for hydrogenation of carbon dioxide (CO2) to methyl alcohol (CH3OH) over Cu-based catalysts. Nano-sized CuO and ZnO catalysts were deposited on TiO2 support using a co-precipitation (CP) method (CuO-ZnO/TiO2), where the thermal treatment of TC and the particle size of TiC2 are optimized on CO2 conversion under different reaction temperature and contact time. Direct hydrogenation of CO2 to CH3OH over CuO-ZnO/TiO2 catalysts was achieved and the maximum selectivity (22%) and yield (18.2%) of CH3OH were obtained in the range of reaction temperature 210-240 degrees C under the 30 bar. The selectivity was readily increased by increasing the flow rate, which does not affect much to the CO2 conversion and CH3OH yield.

Hybrid and Etch-Less Electrooptic Waveguide Modulator Based on Photo-Bleaching and Strain Induced Optical Waveguide Technique in Polymer

A hybrid and etchless electrooptic (EO) polymer waveguide modulator based on both a photo-bleaching-induced optical waveguide (PBOW) and a strain-induced optical waveguide (SIOW) is described. The SIOW is defined by a metal strip line stressor deposited on top of the upper cladding that introduces the refractive index change within the core region. The PBOW technique is used to form an optical waveguide which is based on a photo-bleaching process, known as a photo-oxidation that is an irreversible decomposition of EO material, resulting in a permanent decrease in index of refraction. It is shown that this proposed fabrication idea combining two etchless techniques can be applicable to a wide range of polymer photonic integrated circuits. Preliminary results obtained from fabricated devices reveal that their half-wave voltage are ranging from 8 V to 10 V, their extinction ratio exhibits more than 15 dB, and the fiber-to-waveguide-to-lens loss is estimated to be ~9.5 dB for TM polarization at 1.55/m wavelength in the active interaction of ~1.5 cm long.

Surface Characterization According to the Bias Voltage of the TiAgN Coating Film Layer Formed by the AIP Process

The implanting of metal products is performed with numerous surface treatments because of toxicity and adhesion. Recently, the surface modification of metal products has been actively studied by coating the surface of the TiC or TiN film. We prepared a Ti(10%)Ag Target which may be used in dental oral material by, using the AIP(arc ion plating) system TiAgN coating layer that was deposited on Ti g.23. The purpose of this study was to establish the optimal bias voltage conditions of the coated TiAgN layer formed by the AIP process. The TiAgN coatings were prepared with different bias voltage parameters (0V to -500V) to investigate the effect of bias voltage on their mechanical and chemical properties. The SEM(scanning electron microscope), EDS(energy dispersive X-ray spectrometer), XRD(X-ray diffraction), micro-hardness, and potentiodynamic polarization were measured and the surface characteristics of the TiAgN coating layers were evaluated. The TiAgN coating layer had different mechanical characteristics based on the bias voltage, which also showed differences in thickness and composition.