• 한국세라믹학회지
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• 제42권4호
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• pp.245-250
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• 2005

단결정 사파이어 (0001) 기판 위에 저가의 초산아연(Zinc Acetate Dehydrate; ZAH) 전구체를 이용하여 초음파 열분해법과 Ar 가스를 이용한 ZnO 박막을 성장시켰다. Thermogravimetry-Differential Scanning Calorimetry(TG-DSC) 초산아연의 열분해 과정을 조사하여 $380^{\circ}C$ 이상에서 ZnO로 분해되는 것을 확인하였다. $380-700^{\circ}C$에서 증착된 ZnO 박막은 모두 ZnO (002), (101) 결정면으로 부터의 회절피크를 보여주고 있었으며, $400^{\circ}C$ 박막의 경우 c-압축 스트레인 ${\Sigma}Z=0.2\%$, 압축 응력 $\sigma=-0.907\;GPa$이 작용하고 있음을 알 수 있었다. 전자 현미경을 이용한 미세 구조의 관찰을 통하여 $380-600^{\circ}C$에서는 초산아연과 ZnO 초미세 입자가 혼합된 aggregate 형태의 결정립을 형성하고 있었으며, nanoblade 형태의 미세구조를 보였다. 한편 $700^{\circ}C$에서 증착된 박막내의 결정립은 찌그러진 육방정계의 형태를 취하고 있으며, 10-25nm 정도의 부결정림 초미세 ZnO 입자로 이루어져 있음을 알 수 있었다. 초미세 입자의 형성을 임의 핵형성 기구(random nucleation mechanism)로 설명하였고, photoluminescence(PL) 측정을 통하여 광 특성을 조사하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.127.1-127.1
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• 2011

In this paper, ZnO:Al thin films with c-axis preferred orientation were prepared on Soda lime glass substrates by RF magnetron sputtering technique. AZO 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 substrate temperature conditions variously, structural and electrical characteristics were measured. For the manufacture of the AZO were vapor-deposited in the named order. It is well-known that post-annealing is an important method to improve crystal quality. For the annealing process, the dislocation nd other defects arise in the material and adsorption/decomposition occurs. The XRD patterns of the AZO films deposited with grey theory prediction design, annealed in a vacuum ambient($2.0{\times}10-3$Torr)at temperatures of 200, 300, 400 and $500^{\circ}C$ for a period of 30min. The diffraction patterns of all the films show the AZO films had a hexagonal wurtzite structure with a preferential orientation along the c-axis perpendicular to the substrate surface. As can be seen, the (002)peak intensities of the AZO films became more intense and sharper when the annealing temperature increased. On the other hand, When the annealing temperature was $500^{\circ}C$ the peak intensity decreased. The surface morphologies and surface toughness of films were examined by atomic force microscopy(AFM, XE-100, PSIA). Electrical resistivity, Gall mobility and carrier concentration were measured by Hall effect measuring system (HL5500PC, Accent optical Technology, USA). The optical absorption spectra of films in the ultraviolet-visibleinfrared( UV-Vis-IR) region were recorder by the UV spectrophotometer(U-3501, Hitachi, Japan). The resistivity, carrier concentration, and Hall mobility of ZnS deposited on glass substrate as a function of post-annealing.

• 한국재료학회지
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• 제30권4호
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• pp.204-210
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• 2020

ZnO thin films are of considerable interest because they can be customized by various coating technologies to have high electrical conductivity and high visible light transmittance. Therefore, ZnO thin films can be applied to various optoelectronic device applications such as transparent conducting thin films, solar cells and displays. In this study, ZnO rod and thin films are fabricated using aqueous chemical bath deposition (CBD), which is a low-cost method at low temperatures, and environmentally friendly. To investigate the structural, electrical and optical properties of ZnO for the presence of citrate ion, which can significantly affect crystal form of ZnO, various amounts of the citrate ion are added to the aqueous CBD ZnO reaction bath. As a result, ZnO crystals show a nanorod form without citrate, but a continuous thin film when citrate is above a certain concentration. In addition, as the citrate concentration increases, the electrical conductivity of the ZnO thin films increases, and is almost unchanged above a certain citrate concentration. Cu(In,Ga)Se₂ (CIGS) solar cell substrates are used to evaluate whether aqueous CBD ZnO thin films can be applicable to real devices. The performance of aqueous CBD ZnO thin films shows performance similar to that of a sputter-deposited ZnO:Al thin film as top transparent electrodes of CIGS solar cells.

• 한국진공학회지
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• 제20권4호
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• pp.300-306
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• 2011

본 연구는 편극 패턴된 강유전체 단결정 $LiNbO_3$ (0001) 기판에 광화학적 환원반응을 이용하여 금속(Au, Ag) 나노입자를 증착시키고, 금속 입자의 종류와 표면의 극성에 따른 나노입자의 표면 분포를 원자간력현미경(AFM)으로 조사하였다. 전극 인가에 의해 주기적으로 편극 패턴된 강유전체 단결정 $LiNbO_3$ (periodically polarity-patterned $LiNbO_3$: PPLN)을 기판으로 사용하였으며, PPLN의 각 영역의 편극 방향은 Piezoresponse force microscopy로 확인하였다. 금속(Ag, Au) 나노 입자는 금속이 포함된 수용액에 PPLN 기판을 넣고, 자외선 램프로 30초에서 3분간 노출시켜 광환원 반응으로 기판에 증착시켰다. 시료 성장후, 공기 중에서 AFM을 이용하여 나노입자의 형태, 크기, 및 표면분포를 조사하였다. Ag 입자의 경우, -Z 편극 영역보다 +Z 편극 영역에 크고 밀도가 높은 나노 입자가 증착되었으며, 특히 편극 경계 부분에 가장 큰 Ag 나노입자가 증착되어, 나노선 모양으로 성장됨이 확인되었다. 그러나 Au 입자의 경우는 편극 경계부분에 입자가 증착되는 경향이 없었다. 두 입자 모두 자외선 노출시간이 증가함에 따라, 증착된 나노입자의 크기는 증가하는 경향을 보였다. 이와 같이 증착된 금속 나노입자가 강유전체의 표면편극에 따라 다른 분포로 성장되는 것을 강유전체 표면 극성에 따른 표면 밴드구조 변화, 광전 효과 및 표면의 전기장의 불균일성에 의한 수용액 속의 금속 양이온과 자외선에 의해 생성된 전자와의 광화학적 반응에 대한 모델로 논의할 것이다.

• 공업화학
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• 제5권6호
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• pp.1036-1043
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• 1994

폴리에칠렌을 가교시키는 방법으로서 silane에 의한 가교를 행하였다. Silane 가교는 압출기를 이용하여 $200{\sim}210^{\circ}C$ 용융온도에서 반응압출시켜 vinyltrimethoxysilane(VTMOS)를 PE 주쇄에 그라프트시킨 후, 3가지 silane 가교조건($80^{\circ}C$ 온수가교, $80^{\circ}C$ air oven 가교, 상온대기방치 가교)으로써 물 또는 수분에 노출시켜 가교를 완성하였다. Silane 가교된 폴리에칠렌의 결정 용융온도(Tm)의 변화, 밀도의 변화, 가교의 속도 거동을 측정하여 수지의 silane 가교조건에 따른 열적특성 변화를 연구하였다. Silane 가교는 용융상태의 고온에서 가교시키는 과산화물 가교와는 달리 고체상태에서 가교가 일어나기 때문에 그 가교조건에 따라 결정용융온도, 결정도 및 결정성장, 가교속도, 밀도의 변화가 다르고 수지의 종류도 열적특성에 영향을 미침을 알았다. 상온대기방치 가교된 silane 가교 linear low density polyehylene(LLDPE)은 결정이 성장되면서 서서히 가교반응이 진행됨에 따라 DSC에서 2차 용융 피크가 생성되지 않았으며, 재결정화하면 결합된 가교 site의 결정화 방해현상에 의해 결정용융온도가 낮아지는 거동을 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.122-122
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• 1999

Graphite with its advantages of high thermal conductivity, low thermal expansion coefficient, and low elasticity, has been widely used as a structural material for high temperature. However, graphite can easily react with oxygen at even low temperature as 40$0^{\circ}C$, resulting in CO2 formation. In order to apply the graphite to high temperature structural material, therefore, it is necessary to improve its oxidation resistive property. Silicon Carbide (SiC) is a semiconductor material for high-temperature, radiation-resistant, and high power/high frequency electronic devices due to its excellent properties. Conventional chemical vapor deposited SiC films has also been widely used as a coating materials for structural applications because of its outstanding properties such as high thermal conductivity, high microhardness, good chemical resistant for oxidation. Therefore, SiC with similar thermal expansion coefficient as graphite is recently considered to be a g행 candidate material for protective coating operating at high temperature, corrosive, and high-wear environments. Due to large lattice mismatch (~50%), however, it was very difficult to grow thick SiC layer on graphite surface. In theis study, we have deposited thick SiC thin films on graphite substrates at temperature range of 700-85$0^{\circ}C$ using single molecular precursors by both thermal MOCVD and PEMOCVD methods for oxidation protection wear and tribological coating . Two organosilicon compounds such as diethylmethylsilane (EDMS), (Et)2SiH(CH3), and hexamethyldisilane (HMDS),(CH3)Si-Si(CH3)3, were utilized as single source precursors, and hydrogen and Ar were used as a bubbler and carrier gas. Polycrystalline cubic SiC protective layers in [110] direction were successfully grown on graphite substrates at temperature as low as 80$0^{\circ}C$ from HMDS by PEMOCVD. In the case of thermal MOCVD, on the other hand, only amorphous SiC layers were obtained with either HMDS or DMS at 85$0^{\circ}C$. We compared the difference of crystal quality and physical properties of the PEMOCVD was highly effective process in improving the characteristics of the a SiC protective layers grown by thermal MOCVD and PEMOCVD method and confirmed that PEMOCVD was highly effective process in improving the characteristics of the SiC layer properties compared to those grown by thermal MOCVD. The as-grown samples were characterized in situ with OES and RGA and ex situ with XRD, XPS, and SEM. The mechanical and oxidation-resistant properties have been checked. The optimum SiC film was obtained at 85$0^{\circ}C$ and RF power of 200W. The maximum deposition rate and microhardness are 2$mu extrm{m}$/h and 4,336kg/mm2 Hv, respectively. The hardness was strongly influenced with the stoichiometry of SiC protective layers.

• 한국세라믹학회지
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• 제34권1호
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• pp.31-36
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• 1997

유전율이 높고 온도안정성이우수하다고 알려져 있는 Pb(Mg1/3Nb2/3)O3-PbTiO3-Pb(Mg1/2W1/2)O3 계 세라믹스를 산화물혼합법 및 precursor방법으로 제조함에 있어 과잉 MgO의 첨가에 따른 미세구조와 유전특성의 변화에 대하여 조사하였다. MgO를 5mol%이상 과잉첨가하여 100$0^{\circ}C$에 소결한 시편의 유전율은 5000이상이고, -55$^{\circ}C$에서 1$25^{\circ}C$범위에서 변화율은 +25%에서 -5$0^{\circ}C$ 정도를 나타냈다. XRD 분석결과 perovskite상과 Pb2WO5 결정이 주된상이었으며, 소결온도 및 MgO 첨가량이 증가함에 따라 cubic pyrochlore상인 Pb3Nb4O13와 PbWO4는 감소하였다. SEM에 의한 미세구조의 관찰에서 MgO첨가량이 증가함에 따라 결정성장이 촉진되는 것을 알 수 있었으며 이것이 소결온도 증가에 따른 pyrochlore상의 감소와 함께 유전율을 증가시키는 원인이었다. BSE관찰에서 화학성분 분포의 불균일성이 나타났으며, 각각의 소결온도에서 생성되는 결정상과 함께 유전율의 온도의존성을 완만하게 만드는 원인임을 알 수 있었다.

• 한국세라믹학회지
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• 제39권8호
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• pp.721-727
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• 2002

고함량 PbO계 조성 PDP 격벽용 유리의 경우, 광학적, 기계적 및 전기적 물성들을 만족시키며, 동시에 높은 온도에서 열처리공정을 거쳐야 하므로, 유리의 조성-물성-공정상의 trade-off가 발생하여, 이를 극복하기 위한 방안으로서 유리의 결정화가 유효하다. 이에 본 연구에서는 고함량 PbO계 조성 PDP 격벽용 후보 유리계의 최적결정화조건을 확립하고자 열시차분석법(DTA)에 의한 결정화 특성을 연구하였다. $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) 조성계의 유리에 결정핵생성 및 성장을 위해 $TiO_2$를 3 wt%를 첨가한 수, 용융/냉각/분쇄 처리 후 얻어진 유리 분말을 $445^{\circ}C$에서 각각 1∼10시간 열처리하여 핵생성을 시켰으며, 이렇게 얻어진 각 유리 분말은 각기 $5∼25^{\circ}C/min$의 가변 승온속도로 DTA 측정을 하였다. DTA 결정화 피크 온도는 승온속도가 높아짐에 따라 증가하였고, 열처리 시간이 증가함에 따라 감소하였다. Avrami 변수는 1에 근사하는 값이 얻어져서, 표면결정화가 우선하였으며, 최대 핵생성 처리시간은 2시간이었다.

• Asian-Australasian Journal of Animal Sciences
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• 제33권4호
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• pp.568-578
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• 2020

Objective: The objective of this study was to investigate effects of supplementation of culture media from solid-state fermented Isaria cicadae (I. cicadae) on performance, serum biochemical parameters, serum immune indexes, antioxidant capacity and meat quality of broiler chickens. Methods: A total of 648 Arbor Acres male broiler chickens(1 d; average body weight, 42.93±0.47 g) were randomly assigned to 6 treatments, each with six replicates and 18 broiler chickens per replicate. Broiler chickens were fed phase I (d 1 to 21) and phase II (d 22 to 42) diets. The phase I diets were corn and soybean-meal based diets supplemented with 0%, 2%, 4%, 6%, 8%, or 10% culture media from solid-state fermented I. cicadae respectively. The phase II diets were corn and soybean-meal based diets supplemented with 0%, 1.33%, 2.67%, 4.00%, 5.32%, or 6.67% culture media from solid-state fermented I. cicadae respectively. Results: In phase I, the broiler chickens with the supplementation of culture media had increased body weight gain and feed intake (linear and quadratic, p<0.05) with increasing inclusion of culture media. The levels of serum total antioxidant capacity (T-AOC), glutathione (GSH) and superoxide dismutase (SOD) increased linearly (p<0.05). In phase II, levels of serum T-AOC and interleukin-1β increased linearly (p<0.05), and GSH increased (p<0.05). In the kidney, GSH and glutathione peroxidase (GSH-Px) concentrations increased (linear and quadratic, p<0.05) and SOD concentration increased linearly (p<0.05). Compared to the control, shear force and drip loss of breast muscle decreased (linear and quadratic, p<0.05). Drip loss of leg muscle decreased linearly and quadratically (p<0.05). Conclusion: Dietary supplementation of culture media from solid-state fermented I.cicadae which was enriched in both wheat and residual bioactive components of I. cicadae enhanced the growth performance of broiler chickens. It also improved body anti-oxidative status and contributed to improve broiler meat quality.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.363-363
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• 2014

Ruthenium (Ru) has attractive material properties due to its promising characteristics such as a low resistivity ($7.1{\mu}{\Omega}{\cdot}cm$ in the bulk), a high work function of 4.7 eV, and feasibility for the dry etch process. These properties make Ru films appropriate for various applications in the state-of-art semiconductor device technologies. Thus, it has been widely investigated as an electrode for capacitor in the dynamic random access memory (DRAM), a metal gate for metal-oxide semiconductor field effect transistor (MOSFET), and a seed layer for Cu metallization. Due to the continuous shrinkage of microelectronic devices, better deposition processes for Ru thin films are critically required with excellent step coverages in high aspect ratio (AR) structures. In these respects, atomic layer deposition (ALD) is a viable solution for preparing Ru thin films because it enables atomic-scale control of the film thickness with excellent conformality. A recent investigation reported that the nucleation of ALD-Ru film was enhanced considerably by using a zero-valent metallorganic precursor, compared to the utilization of precursors with higher metal valences. In this study, we will present our research results on the synthesis and characterization of novel ruthenium complexes. The ruthenium compounds were easy synthesized by the reaction of ruthenium halide with appropriate organic ligands in protic solvent, and characterized by NMR, elemental analysis and thermogravimetric analysis. The molecular structures of the complexes were studied by single crystal diffraction. ALD of Ru film was demonstrated using the new Ru metallorganic precursor and O2 as the Ru source and reactant, respectively, at the deposition temperatures of $300-350^{\circ}C$. Self-limited reaction behavior was observed as increasing Ru precursor and O2 pulse time, suggesting that newly developed Ru precursor is applicable for ALD process. Detailed discussions on the chemical and structural properties of Ru thin films as well as its growth behavior using new Ru precursor will be also presented.