• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.87-87
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• 2011

Oxide semiconductors are attractive materials for thin-film electronics and optoelectronics due to compatibility with synthesis on large-area, glass and flexible substrate. However, development of thin-film electronics has been hampered by the limited number of semiconducting oxides that are p-type. We report on the effect of the oxygen partial pressure ratio in the gas mixture on the electrical and optical properties of spinel Mg:$ZnCo_2O_4$ thin films deposited at room temperature using RF sputtering, that exhibit p-type conduction. The thin-films are deposited at room temperature in a background of oxygen using a polycrystalline Mg:$ZnCo_2O_4$ ablation target. The p-type conduction is confirmed by positive Seebeck coefficient and positive Hall coefficient. The electrical resistivity and carrier concentration in on dependent Mg:$ZnCo_2O_4$ thin films were found to be dependent on the oxygen partial pressure ratio. As a result, it is revealed that the Mg:$ZnCo_2O_4$ thin-films were greatly influenced on the electrical and optical properties by the oxygen partial pressure condition. The visible region of the spectrum of 36~85%, and hole mobility of 1.1~3.7 $cm^2$/Vs, were obtained.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권1호
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• pp.39-43
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• 2016

The structural, electrical properties of Ga doped MgZnO transparent conductive oxide (TCO) films by ratio-frequency(RF) magnetron sputtering were investigated. Ga doped MgZnO TCO films were deposited on the sapphire substrates at $200^{\circ}C$ varying growth thickness 200 to 600 nm. The optical properties of Ga doped MgZnO TCO films were showed above 85% transmittance from 300 to 1000 nm region. In addition, the current density ($J_{SC}$) of $Cu(In,Ga)Se_2$ (CIGS) solar cells was improved by using the MgZnO:Ga films of 500 nm thickness because of outstanding electrical properties. The $Cu(In,Ga)Se_2$ solar cells with MgZnO:Ga transparent conducing layer yielded an efficiency of 9.8% with current density ($31.8mA/cm^2$), open circuit voltage (540.2 V) and fill factor (62.2) under AM 1.5 illumination.

• Corrosion Science and Technology
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• 제7권3호
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• pp.152-157
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• 2008

New wrought magnesium alloys have increasingly been developed in recent years for the automotive industry due to their high potential as structural materials for low density and high strength/weight ratio demands. However, their poor mechanical properties and low corrosion resistance have led to a search for new kinds of magnesium alloys with better strength, ductility, and high corrosion resistance. The main objective of this research is to investigate the corrosion behaviour of new magnesium alloys: Mg-Zn-Ag (ZQ), Mg-Zn-Mn-Si (ZSM) and Mg-Zn-Mn-Si-Ca (ZSMX). These ZQ6X, ZSM6X1, and ZSM651+YCa alloys were prepared using hot extrusion. AC, DC polarization and immersion tests were carried out on the extruded rods. Microstructure was examined using optical and electron microscopy (SEM) and EDS. The addition of silver decreased the corrosion resistance. The additions of silicon and calcium also affected the corrosion behaviour. These results can be explained by the effects of alloying elements on the microstructure of Mg-Zn alloys such as grain size and precipitates caused by the change in precipitation and recrystallisation behaviour.

• 자원리싸이클링
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• 제14권3호
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• pp.63-67
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• 2005

최근 고품위 TV 및 고정세도 디스플레이용으로 화상의 정세도를 향상시키기 위해 수평주파수를 높이려는 경향이 있어, 편향 요크용 페라이트 코아에는 고주파수 영역에 있어서도 코아로스가 낮은 재료가 요구되고 있는 실정이다. Mg-Zn 페라이트에 있어서 화학조성 및 프로세스가 미세구조에 미치는 영향에 착안하여 저온 소결화를 하였다. 저손실인 Mg-Zn계 te에 Cu에 첨가하였다. MgO, ZnO, Fe$_2O_3$, CuO를 선택한 후 조성비의 변화를 두며 CuO를 MgO로 치환하였다. 이 시료를 980$^{\circ}C$~1350$^{\circ}C$까지 3시간 소결하고, 투자율, 전력손실, 수축률, 코아로스를 측정하였다.

• 한국분말재료학회지
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• 제13권6호
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• pp.427-431
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• 2006

Mg-4.3Zn-0.7Y (at%) alloy powders were prepared using an industrial scale gas atomizer, followed by warm extrusion. The powders were almost spherical in shape. The microstructure of atomized powders and those extruded bars was examined using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscope (EDS) and X-ray Diffractometer (XRD). The grain size of the powders was coarsen as the initial powder size increased. After the extrusion, the grain size became fine due to the severe plastic deformation during the extrusion with the ratio of 10:1. Both the ultimate strength and elongation were enhanced with the decrease of initial particle size.

• 한국세라믹학회지
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• 제32권3호
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• pp.305-312
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• 1995

Thin films of Pb(Mg, Zn)1/3Nb2/3O3 were fabricated by spin coating the Pb-Mg-Zn-Nb-O complex alkoxide sols on(111) Pt-coated MgO (100) planes. It was observed that the content of H2O and the rheological characteristics of sol greatly influenced the orientation of perovskite grains after thin-film formation. A strong preferential orientation of (100)-type planes of the perovskite grains was obtained for the sol aged for 15 days with the molar ratio of H2O to total metal alkoxides=2. As small angle X-ray scattering experiment in the Porod region was performed to correlate the observed preferential orientation with the network structure of precursors at various stage of aging. It was shown that the degree of branching of the Pb-Mg-Zn-Nb-O precursor chain had a direct effect on the preferred oreintation, and weakly branched precursor systems led to highly oriented grains after thin-film formation.

• 한국전기전자재료학회논문지
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• 제33권3호
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• pp.214-218
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• 2020

In this study, Mg_xZn_1-xO thin films, which can be applied not only to active layers of light-emitting devices (LEDs), such as UV-LEDs, but also to solar cells, high mobility field-effect transistors, and power semiconductor devices, are fabricated using the sol-gel method. ZnO and Mg_0.3Zn_0.7O solution synthesized by the sol-gel method and the thin film were grown by spin coating on a Si (100) substrate and sapphire substrate. The solutions are synthesized by dissolving precursor materials in 2-methoxyethanol (2-ME) solvent, and then monoethanolamine (MEA) was added to the mixed solution as a sol stabilizer. Zinc acetate dihydrate is used as a ZnO precursor, while Mg nitrate hexahydrate and Mg acetate tetrahydrate are used as an MgO precursor. Then, the optical and structural characteristics of the fabricated thin films are compared. The molar concentration of the Zn precursor in the solvent is fixed at 0.3 M, and the amount of the Mg precursor is 30% of Mg²⁺/Zn²⁺. The optical characteristics are measured using an UV-vis spectrophotometer, and the transmittance of each wavelength is measured. Structural characteristics are measured using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Composition analyses are performed using energy dispersive X-ray spectroscopy (EDS). The Mg_0.3Zn_0.7O thin film was well formed at the ratio of the Mg precursor added regardless of the type of Mg precursor, and the c-axis of the thin film was decreased, while the band gap was increased to 3.56 eV.

• 한국식품영양과학회지
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• 제30권3호
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• pp.388-394
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• 2001

This study was conducted ton investigate the mineral contents of commercial baby foods. Samples were classified into 4 groups; powdered formula, baby juice product (domestic), juice and paste products (imported) and soymilk-based formula. We analyzed Ca, P, Mg, Na, K, Fe, Cu, Zn contents by atomic absorption spectrophotometer after dry-ashing. The difference of analyzed value versus labeled value and Ca/P ratio of analyzed value were calculated. The difference (%) of analyzed value on the labeled value was Ca: 98.6, P: 121.8, Mg: 146.1, Na: 87.4, K: 104.3, Fe: 104.8, Cu: 120.2, Zn: 109.8 in powdered formula, Mg showed the highest difference among the elements. The Ca/P ratio of powdered formula was 1.41 (1.70-1.99). Baby juice products (domestic) were fortified Ca, Fe and the difference (%) of analyzed value on labeled value of Ca and Fe contents was 131.8, 110.2, respectively. The Ca/P ratio of these was 2.36 (1.64-3.71). Differently the domestic products, imported juice and paste products were not fortified Ca, Fe and its Ca/P ratio was 0.38(0.14-0.59). The difference (%) of analyzed value on the labeled value was Ca: 110.2, Mg: 179.5, Na: 83.7, K: 87.8, Cu: 107.8, Fe: 219.8, Zn: 100.5, P: 126.6 in soymilk-based formula, Fe showed the highest difference among the elements. The Ca/P ratio of soymilk-based formula was 1.17 (1.04-0.39).

• 대한금속재료학회지
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• 제49권2호
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• pp.145-152
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• 2011

Mechanical and property corrosion resistance of Mg-Zn-Y alloys with an atomic ratio of Zn/Y of 6.8 are investigated using optical microscopy, scanning electron microscopy, transmission electron microscopy, uniaxial tensile test and corrosion test with immersion and dynamic potentiometric tests. The alloys showed an in-situ composite microstructure consisting of ${\alpha}$-Mg and icosahedral phase (I-phase) as a strengthening phase. As the volume fraction of the I-phase increases, the yield and tensile strengths of the alloys increase while maintaining large elongation (26~30%), indicating that I-phase is effective for strengthening and forms a stable interface with surrounding ${\alpha}$-Mg matrix. The presence of I-phase having higher corrosion potential than ${\alpha}$-Mg, decreased the corrosion rate of the cast alloy up to I-phase volume fraction of 3.7%. However further increase in the volume fraction of the I-phase deteriorates the corrosion resistance due to enhanced internal galvanic corrosion cell between ${\alpha}$-Mg and I-phase.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.121-121
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• 2010

ZnO is a promising material for the application of high efficiency light emitting diodes with short wavelength region for its large bandgap energy of 3.37 eV which is similar to GaN (3.39 eV) at room temperature. The large exciton binding energy of 60 meV in ZnO provide provides higher efficiency of emission for optoelectronic device applications. Several ZnO/ZnMgO multiple quantum well (MQW) structures have been grown on various substrates such as sapphire, GaN, Si, and so on. However, the achievement of high quality ZnO/ZnMgO MQW structures has been somehow limited by the use of lattice-mismatched substrates. Therefore, we propose the optical properties of ZnO/ZnMgO multiple quantum well (MQW) structures with different well widths grown on lattice-matched ZnO substrates by molecular beam epitaxy. Photoluminescence (PL) spectra show MQW emissions at 3.387 and 3.369 eV for the ZnO/ZnMgO MQW samples with well widths of 2 and 5 nm, respectively, due to the quantum confinement effect. Time-resolved PL results show an efficient photo-generated carrier transfer from the barrier to the MQWs, which leads to an increased intensity ratio of the well to barrier emissions for the ZnO/ZnMgO MQW sample with the wider width. From the power-dependent PL spectra, we observed no PL peak shift of MQW emission in both samples, indicating a negligible built-in electric field effect in the ZnO/$Zn_{0.9}Mg_{0.1}O$ MQWs grown on lattice-matched ZnO substrates.