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
제19권 제1호 (2009년 1월) 10건
1.
2009.01
구독 인증기관 무료, 개인회원 유료
In this study, the stress-strain response and the cracking behaviors of ITO film on a PET substrate are investigated. The cracking behaviors of ITO thin films deposited on a thermoplastic semi-crystalline polymer developed for flexible display applications was investigated by means of tensile experiments equipped with an electrical measurement apparatus and an in-situ optical microscope. Electrical resistance increased gradually in the elastic-to-plastic transition region of the stress strain curves and cracks formed. Numerous cracks were found in this region, and the increase of the resistance was linked to the cracking of ITO thin films. Upon loading, the initial cracks perpendicular to the tensile axis were observed at about 1% of the total strain. They propagated to the entire sample width as the strain increased. The spacing between the horizontal cracks is thought to be determined by the fracture strength and the thickness of the ITO film as well as by the interfacial strength between the ITO and PET. The effect of the strain rate on the cracking behavior was also investigated. The crack density increased as the strain increased. The spacing between the horizontal cracks (perpendicular to the stress axis) increased as the strain rate decreased. The increase of the crack density as the strain rate decreased can be attributed to the higher fraction of the plastic strain to the total strain at a given total strain. The higher critical strain for the onset of the increase in the resistance and the crack initiation of the ITO/PET with a thinner ITO film (300 ohms/sq.) suggests a higher strength of the thinner ITO film.
4,000원
2.
2009.01
구독 인증기관 무료, 개인회원 유료
TFT-LCD is the most popular type of flat display panel in the information technology field. The back light unit is a main part of the structure of a TFT-LCD panel. Occasionally, studies have shown that failures of the CCFL of the BLU occur due to the poor weld characteristics of these materials. The aim of this study was to prepare some technical data and to characterize a microjoined electrode for the CCFL. Microstructure examinations, microhardness measurements, resistance measurements and microtensile tests of the microjoined electrode were carried out. The result indicates that a large amount of grain coarsening exists in the heat-affected zone (HAZ) of the weld between the cup and the pin. This grain coarsening of the HAZ between the cup and pin is caused by the welding cycle, which may have an influence on the lowest microhardness values. Fracturing of the microjoined electrode also occurred at the HAZ close to the cup between the weld holding the cup and the pin. Additionally, no specific changes of the electrical resistance among the cup, pin, and lead wire themselves or in the microjoined electrode were observed.
4,000원
3.
2009.01
구독 인증기관 무료, 개인회원 유료
A semi-empirical method to estimate the surface tension of molten alloys at different oxygen partialpressures is suggested in this study. The surface tension of molten Ag-Sn and Ag-Cu alloys were calculatedusing the Butler equation with the surface tension value of pure substance at a given oxygen partialpressure. The oxygen partial pressure ranges were 2.86×10-12－1.24×10-9Pa for the Ag-Sn system and2.27×10-11－5.68×10-4 Pa for the Ag-Cu system. In this calculation, the interactions of the adsorbed oxygenwith other metallic constituents were ignored. The calculated results of the Ag-Sn alloys were in reasonableaccordance with the experimental data within a difference of 8%. For the Ag-Cu alloy system at a higheroxygen partial pressure, the surface tension initially decreased but showed a minimum at XAg = 0.05 to increaseas the silver content increased. This behavior appears to be related to the oxygen adsorption and thecorresponding surface segregation of the constituent with a lower surface tension. Nevertheless, the calculatedresults of the Ag-Cu alloys with the present model were in good agreement with the experimental data withina difference of 10%.
4,000원
4.
2009.01
구독 인증기관 무료, 개인회원 유료
The influence of various surface morphologies on the mechanical strength of silicon substrates was investigated in this study. The yield for the solar cell industry is mainly related to the fracturing of silicon wafers during the manufacturing process. The flexural strengths of silicon substrates were influenced by the density of the pyramids as well as by the size and the rounded surface of the pyramids. To characterize and optimize the relevant texturing process in terms of mechanical stability and the fabrication yield, the mechanical properties of textured silicon substrates were investigated to optimize the size and morphology of random pyramids. Several types of silicon substrates were studied, including the planar type, a textured surface with large and small pyramids, and a textured surface with rounded pyramids. The surface morphology and a cross-section of the as-textured and fractured silicon substrates were investigated by scanning electron microscopy.
4,000원
5.
2009.01
구독 인증기관 무료, 개인회원 유료
Indium Gallium Zinc Oxide (IGZO) thin films were deposited onto 300 nm-thick oxidized Si substrates and glass substrates by direct current (DC) magnetron sputtering of IGZO targets at room temperature. FESEM and XRD analyses indicate that non-annealed and annealed IGZO thin films exhibit an amorphous structure. To investigate the effect of an annealing treatment, the films were thermally treated at 300˚C for 1hr in air. The IGZO TFTs structure was a bottom-gate type in which electrodes were deposited by the DC magnetron sputtering of Ti and Au targets at room temperature. The non-annealed and annealed IGZO TFTs exhibit an Ion/Ioff ratio of more than 105. The saturation mobility and threshold voltage of nonannealed IGZO TFTs was 4.92×10-1cm2/V·s and 1.46V, respectively, whereas these values for the annealed TFTs were 1.49×10-1cm2/V· and 15.43V, respectively. It is believed that an increase in the surface roughness after an annealing treatment degrades the quality of the device. The transmittances of the IGZO thin films were approximately 80%. These results demonstrate that IGZO thin films are suitable for use as transparent thin film transistors (TTFTs).
3,000원
6.
2009.01
구독 인증기관 무료, 개인회원 유료
Ni/4H-SiC Field Plate Schottky 다이오드 제작 시 과도 식각에 의해 형성된 Nickeltitanium 이중 금속 Schottky 접합 특성과 공정 개선 연구
Silicon carbide (SiC) is a promising material for power device applications due to its wide band gap(3.26 eV for 4H-SiC), high critical electric field and excellent thermal conductivity. The Schottky barrier diodeis the representative high-power device that is currently available commercially. A field plate edge-terminated4H-SiC was fabricated using a lift-off process for opening the Schottky contacts. In this case, Ni/Ti dual-metalcontacts were unintentionally formed at the edge of the Schottky contacts and resulted in the degradation ofthe electrical properties of the diodes. The breakdown voltage and Schottky barrier height (SBH, ΦB) was 107V and 0.67eV, respectively. To form homogeneous single-metal Ni/4H-SiC Schottky contacts, a deposition andetching method was employed, and the electrical properties of the diodes were improved. The modified SBDsshowed enhanced electrical properties, as witnessed by a breakdown voltage of 635V, a Schottky barrier heightof ΦB=1.48eV, an ideality factor of n=1.04 (close to one), a forward voltage drop of VF=1.6V, a specific onresistance of Ron=2.1mΩ-cm2 and a power loss of PL=79.6Wcm-2.
4,000원
7.
2009.01
구독 인증기관 무료, 개인회원 유료
Inorganic-organic composite thin-film-transistors (TFTs) of ZnO nanowire/Poly(3-hexylthiophene)(P3HT) were investigated by changing the nanowire densities inside the composites. Crystalline ZnO nanowireswere synthesized via an aqueous solution method at a low temperature, and the nanowire densities inside thecomposites were controlled by changing the ultrasonifiaction time. The channel layers were prepared withcomposites by spin-coating at 2000rpm, which was followed by annealing in a vacuum at 100oC for 10 hours.Au/inorganic-organic composite layer/SiO2 structures were fabricated and the mobility, Ion/Ioff ratio, andthreshold voltage were then measured to analyze the electrical characteristics of the channel layer. Comparedwith a P3HT TFT, the electrical properties of TFT were found to be improved after increasing the nanowiredensity inside the composites. The mobility of the P3HT TFT was approximately 10-4cm2/V·s. However, themobility of the ZnO nanowire/P3HT composite TFT was increased by two orders compared to that of theP3HT TFT. In terms of the Ion/Ioff ratio, the composite device showed a two-fold increase compared to thatof the P3HT TFT.
3,000원
8.
2009.01
구독 인증기관 무료, 개인회원 유료
Silicon dioxide as gate dielectrics was grown at 400˚C on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of O2 and N2O to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature N2O annealing, nitrogen can be supplied to the Si/SiO2 interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/SiO2 interface by plasma oxidation as the N2O molecule is broken in the plasma and because a dense Si-N bond is formed at the SiO2 surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the Si/SiO2 interface by the plasma oxidation of mixtures of O2/N2O gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.
4,000원
9.
2009.01
구독 인증기관 무료, 개인회원 유료
Conjugated nanocrystals using CdSe/ZnS core/shell nanocrystal quantum dots modified by organic linkers and glucose oxidase (GOx) were prepared for use as biosensors. The trioctylphophine oxide (TOPO)-capped QDs were first modified to give them water-solubility by terminal carboxyl groups that were bonded to the amino groups of GOx through an EDC/NHS coupling reaction. As the glucose concentration increased, the photoluminescence intensity was enhanced linearly due to the electron transfer during the enzymatic reaction. The UV-visible spectra of the as-prepared QDs are identical to that of QDs-MAA. This shows that these QDs do not become agglomerated during ligand exchanges. A photoluminescence (PL) spectroscopic study showed that the PL intensity of the QDs-GOx bioconjugates was increased in the presence of glucose. These glucose sensors showed linearity up to approximately 15 mM and became gradually saturated above 15 mM because the excess glucose did not affect the enzymatic oxidation reaction past that amount. These biosensors show highly sensitive variation in terms of their photoluminescence depending on the glucose concentration.
4,000원
10.
2009.01
구독 인증기관 무료, 개인회원 유료
Multi-walled carbon nanotubes (MWNTs) were synthesized on different substrates (bare Si and SiO2/Si substrate) to investigate dye-sensitized solar cell (DSSC) applications as counter electrode materials. The synthesis of MWNTs samples used identical conditions of a Fe catalyst created by thermal chemical vapor deposition at 900˚C. It was found that the diameter of the MWNTs on the Si substrate sample is approximately 5~10nm larger than that of a SiO2/Si substrate sample. Moreover, MWNTs on a Si substrate sample were well-crystallized in terms of their Raman spectrum. In addition, the MWNTs on Si substrate sample show an enhanced redox reaction, as observed through a smaller interface resistance and faster reaction rates in the EIS spectrum. The results show that DSSCs with a MWNT counter electrode on a bare Si substrate sample demonstrate energy conversion efficiency in excess of 1.4 %.
3,000원
