간행물
한국재료학회지 KCI 등재 SCOPUS Korean Journal of Materials Research
- 발행기관 한국재료학회
- 자료유형 학술지
- 간기 월간
- ISSN 2799-8525 (Print)2799-8681 (Online)
- 수록기간 1991 ~ 2024
- 주제분류 공학 > 재료공학 공학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
제20권 제8호 (2010년 8월) 9건
1.
2010.08
구독 인증기관 무료, 개인회원 유료
We studied the influence of different types of metal electrodes on the performance of solution-processed zinc tin oxide (ZTO) thin-film transistors. The ZTO thin-film was obtained by spin-coating the sol-gel solution made from zinc acetate and tin acetate dissolved in 2-methoxyethanol. Various metals, Al, Au, Ag and Cu, were used to make contacts with the solution-deposited ZTO layers by selective deposition through a metal shadow mask. Contact resistance between the metal electrode and the semiconductor was obtained by a transmission line method (TLM). The device based on an Al electrode exhibited superior performance as compared to those based on other metals. Kelvin probe force microscopy (KPFM) allowed us to measure the work function of the oxide semiconductor to understand the variation of the device performance as a function of the types metal electrode. The solution-processed ZTO contained nanopores that resulted from the burnout of the organic species during the annealing. This different surface structure associated with the solution-processed ZTO gave a rise to a different work function value as compared to the vacuum-deposited counterpart. More oxygen could be adsorbed on the nanoporous solution-processed ZTO with large accessible surface areas, which increased its work function. This observation explained why the solution-processed ZTO makes an ohmic contact with the Al electrode.
4,000원
2.
2010.08
구독 인증기관 무료, 개인회원 유료
Indium doped SnO2 thick films for gas sensors were fabricated by a screen printing method on alumina substrates. The effects of indium concentration on the structural and morphological properties of the SnO2 were investigated by X-ray diffraction and Scanning Electron Microscope. The structural properties of the SnO2:In by X-ray diffraction showed a (110) dominant SnO2 peak. The size of SnO2 particles ranged from 0.05 to 0.1 μm, and SnO2 particles were found to contain many pores, according to the SEM analysis. The thickness of the indium-doped SnO2 thick films for gas sensors was about 20 μm, as confirmed by cross sectional SEM image. Sensitivity of the SnO2:In gas sensor to 2000 ppm of CO2 gas and 50 ppm of H2S gas was investigated for various indium concentrations. The highest sensitivity to CO2 gas and H2S gas of the indium-doped SnO2 thick films was observed at the 8 wt% and 4 wt% indium concentration, respectively. The good sensing performances of indium-doped SnO2 gas sensors to CO2 gas were attributed to the increase of oxygen vacancies and surface area in the SnO2:In. The SnO2:In gas sensors showed good selectivity to CO2 gas.
3,000원
3.
2010.08
구독 인증기관 무료, 개인회원 유료
Mo thin films were used for the back electrode because of the low resistivity in the Mo/CuInGaSe2 contact inchalcopyrite solar cells. 1µm thick Mo thin films were deposited on soda lime glass by varying the Ar pressure with the dc-magnetron sputtering process. The effects of the Ar pressure on the morphology of the Mo back electrode were studied andthe relationships between the morphology and electro-optical properties, namely, the resistivity as well as the reflectance of theMo thin films, were investigated. The resitivity increased from 24µΩ·cm to 11833µΩ·cm; this was caused by the increasedsurface defect and low crystallinity as the Ar pressure increased from 3×10−3 to 3×10−2Torr. The surface morphologies ofthe Mo thin films changed from somewhat coarse fibrous structures to irregular and fine celled strucutures with increased surfacecracks along the cell boundaries, as the Ar pressure increased from 3×10−3 to 3×10−2Torr. The changes of reflectances in thevisible light range with Ar pressures were mainly attributed to the surface morphological changes of the Mo thin films. Thereflectance in the visible light range showed the highest value of 45% at 3×10−3Torr and decreased to 18.5% at 3×10−2Torr.
4,000원
4.
2010.08
구독 인증기관 무료, 개인회원 유료
As a starting material, BCP (biphasic calcium phosphate) nano powder was synthesized by a hydrothermal microwave-assisted process. A highly porous BCP scaffold was fabricated by the sponge replica method using 60 ppi (pore per inch) of polyurethane sponge. The BCP scaffold had interconnected pores ranging from 100 μm to 1000 μm, which were similar to natural cancellous bone. To realize the antibacterial property, a microwave-assisted nano Ag spot coating process was used. The morphology and distribution of nano Ag particles were different depending on the coating conditions, such as concentration of the AgNO3 solution, microwave irradiation times, etc. With an increased microwave irradiation time, the amount of coated nano Ag particles increased. The surface of the BCP scaffold was totally covered with nano Ag particles homogeneously at 20 seconds of microwave irradiation time when 0.6 g of AgNO3 was used. With an increased amount of AgNO3 and irradiation time, the size of the coated particles increased. Antibacterial activities of the solution extracted from the Ag-coated BCP scaffold were examined against gram-negative (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus). When 0.6 g of AgNO3 was used for coating the Ag-coated scaffold, it showed higher antibacterial activities than that of the Ag-coated scaffold using 0.8 g of AgNO3.
4,000원
5.
2010.08
구독 인증기관 무료, 개인회원 유료
This study shows the effects of deionized (DI) rinse and oxide HF wet etch processes on silicon substrate during a photolithography process. We found a fail at the wafer center after DI rinse step, called Si pits, during the fabrication of a complementary metal-oxide-semiconductor (CMOS) device. We tried to find out the mechanism of the Si pits by using the silicon wafer on CMOS fabrication and analyzing the effects of the friction charge induced by the DI rinsing. The key parameters of this experiment were revolution per minute (rpm) and time. An incubation time of above 10 sec was observed for the formation of Si pits and the rinsing time was more effective than rpm on the formation of the Si pits. The formation mechanism of the Si pits and optimized rinsing process parameters were investigated by measuring the charging level using a plasma density monitor. The DI rinse could affect the oxide substrate by a friction charging phenomenon on the photolithography process. Si pits were found to be formed on the micro structural defective site on the Si substrate under acceleration by developed and accumulated charges during DI rinsing. The optimum process conditions of DI rinse time and rpm could be established through a systematic study of various rinsing conditions.
4,000원
6.
2010.08
구독 인증기관 무료, 개인회원 유료
In this study, activated carbon (AC) as a carbon source was modified with different concentrations of cobalt chloride (CoCl2) to prepare a Co-AC composite, and it was used for the preparation of Co-AC/TiO2 composites with titanium oxysulfate (TOS) as the titanium precursor. The physicochemical properties of the prepared Co-AC/TiO2 composites were characterized by N2 adsorption at 77 K, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The photocatalytic treatments of organic dyes were examined under an irradiation of visible light with different irradiation times. N2 adsorption data showed that the composites had decreased surface area compared with the pristine AC, which was 389 m2/g. From the XRD results, the Co-AC/TiO2 composites contained a mixturephase structuresof anatase and rutile, but a cobalt oxide phase was not detected in the XRD pattern. The EDX results of the Co-AC/TiO2 composites confirmed the presence of various elements, namely, C, O, Ti, and Co. Subsequently, the decomposition of methylene orange (MO, C14H14N3NaO3S) and rhodamine B (Rh.B, C28H31ClN2O3) in an aqueous solution, respectively, showed the combined effects of an adsorption effect by AC and the photo degradation effect by TiO2. Especially, the Co particles in the Co-AC/TiO2 composites could enhance the photo degradation behaviors of TiO2 under visible light.
4,000원
7.
2010.08
구독 인증기관 무료, 개인회원 유료
The selenization process has been a promising method for low-cost and large-scale production of high quality CIGS film. However, there is the problem that most Ga in the CIGS film segregates near the Mo back contact. So the solar cell behaves like a CuInSe2 and lacks the increased open-circuit voltage. In this study we investigated the Ga distribution in CIGS films by using the Ga2Se3 layer. The Ga2Se3 layer was applied on the Cu-In-Ga metal layer to increase Ga content at the surface of CIGS films and to restrict Ga diffusion to the CIGS/Mo interface with Ga and Se bonding. The layer made by thermal evaporation was showed to an amorphous Ga2Se3 layer in the result of AES depth profile, XPS and XRD measurement. As the thickness of Ga2Se3 layer increased, a small-grained CIGS film was developed and phase seperation was showed using SEM and XRD respectively. Ga distributions in CIGS films were investigated by means of AES depth profile. As a result, the [Ga]/[In+Ga] ratio was 0.2 at the surface and 0.5 near the CIGS/Mo interface when the Ga2Se3 thickness was 220 nm, suggesting that the Ga2Se3 layer on the top of metal layer is one of the possible methods for Ga redistribution and open circuit voltage increase.
4,000원
8.
2010.08
구독 인증기관 무료, 개인회원 유료
Nano sized SiC particles (270 nm) are easily agglomerated in nickel sulfamate electrolytic bath during a composite electrodeposition process. The agglomeration of nano particles in composite coatings can significantly reduce the mechanical properties of the composite coatings. In this study, Ni-SiC nano composite coatings were fabricated using a conventional electrodeposition process with the aid of ultrasound. Nano particles were found to be distributed homogeneously with reduced agglomeration in the ultrasonicated samples. Substantial improvements in mechanical properties were observed in the composite coatings prepared in presence of ultrasound over those without ultrasound. Ni-SiC composite coatings were prepared with variable ultrasonic frequencies ranging from 24 kHz to 78 kHz and ultrasonic powers up to 300 watts. The ultrasonic frequency of 38 kHz with ultrasonic power of 200 watt was revealed to be the best ultrasonic conditions for homogeneous dispersion of nano SiC particles with improved mechanical properties in the composite coatings. The microstructures, phase compositions, and mechanical properties of the composite coatings were observed and evaluated using SEM, XRD, Vickers microhardness, and wear test. The Vickers microhardness of composite coatings under ultrasonic condition was significantly improved as compared to the coatings without ultrasound. The friction coefficient of the composite coating prepared with an ultrasonic condition was also smaller than the pure nickel coatings. A synergistic combination of superior wear resistance and improved microhardness was found in the Ni-SiC composite coatings prepared with ultrasonic conditions.
4,000원
9.
2010.08
구독 인증기관 무료, 개인회원 유료
Transparent ceramics are used in new technology because of their excellent mechanical properties over glasses. Transparent ceramics are nowadays widely used in armor, laser windows, and in high temperature applications. Silicon nitride ceramics have excellent mechanical properties and if transparent silicon nitride is fabricated, it can be widely used. h-BN has a lubricating property and is ductile. Therefore, adding h-BN to silicon nitride ceramics gives a lubricating property and is also machinable. Translucent silicon nitride was fabricated by hot-press sintering (HPS) and 57% transmittance was observed in the near infrared region. A higher wt. % of h-BN in silicon nitride ceramics does not favor transparency. The optical, mechanical, and tribological properties of BN dispersed polycrystalline Si3N4 ceramics were affected by the density, α:β-phase ratio, and content of h-BN in sintered ceramics. The hot pressed samples were prepared from the mixture of α-Si3N4, AlN, MgO, and h-BN at 1850˚C. The composite contained from 0.25 to 2 wt. % BN powder with sintering aids (9% AlN + 3% MgO). A maximum transmittance of 57% was achieved for the 0.25 wt. % BN doped Si3N4 ceramics. Fracture toughness increased and wear volume and the friction coefficient decreased with an increase in BN content. The properties such as transmittance, density, hardness, and flexural strength decreased with an increase in content of h-BN in silicon nitride ceramics.
4,000원
