• Progress in Superconductivity
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• 제13권2호
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• pp.90-96
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• 2011

We investigated the properties of artificial pinning centers of YBCO multilayer films in which $Y_2O_3$ and ZnO nanoparticles are uniformly introduced by using the pulsed laser deposition (PLD) technique. $Y_2O_3$ and ZnO nanoparticles were deposited on top of YBCO buffer layer and the density of nanoparticles was controlled by varying the number of nanoparticle layers. YBCO superconducting layers with total thickness of 250 nm were deposited on top of $Y_2O_3$ and ZnO nanoparticles. Based on analyses of the surface morphology, the transition temperature $T_c$, and the critical current density $J_c$, we discussed the difference between the two kinds of nanoparticles as flux pinning centers.

• 전자공학회논문지A
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• 제30A권10호
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• pp.33-40
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• 1993

A reflection type 16x8 S-SEED array from LP(Low Pressure)-MODVD-grown GaAs/AlGaAs extremely shallow quantum well(ESQW) structures, with 4% Al fraction, has been fabricated. Its intrinsic region consists of 50 pairs of alternating 100.angs. GaAs and 100.angs. $Al_{0.04}$Ga$_{0.96}$As layers. A multilayer reflector stack of $Al_{0.04}$/Ga$_{0.96}$ As(599$\AA$)/AlAs(723$\AA$) was incorporated for the reflection plane below the p-i-n structures. The device processing after the MOCVD growth includes the mesa etching, isolation etching, insulator deposition, p & n metallization, and AR(Anti-Reflection) coating. For switching characteristics of the S-SEED in the form of p-i-n ESQW diode, the maximum optical negative resistance was observed at 856nm. Reflectance measurements showed a change from 15.6% to 43.3% for +0.9V to -6V bias. The maximum contrast ration of the S-SEED array was 2.0 and all the 128 devices showed optical bistability with contrast ratios over 2.4 at 5V reverse bias.

• Transactions on Electrical and Electronic Materials
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• 제8권1호
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• pp.36-40
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• 2007

Inorganic layers, such as SiOxNy and SiOx deposited using plasma sublimation method, were tested as passivation layer for organic thin-film-transistors (OTFTs). OTFTs with bottom-gate and bottom-contact structure were fabricated using pentacene as organic semiconductor and an organic gate insulator. SiOxNy layer gave little change in characteristics of OTFTs, but SiOx layer degraded the performance of OTFTs severely. Inferior barrier properties related to its lower film density, higher water vapor transmission rate (WVTR) and damage due to process environment of oxygen of SiOx film could explain these results. Polyurea and polyvinyl acetates (PVA) were tested as organic passivation layers also. PVA showed good properties as a buffer layer to reduce the damage come from the vacuum deposition process of upper passivation layers. From these results, a multilayer structure with upper SiOxNy film and lower PVA film is expected to be a superior passivation layer for OTFTs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.197-197
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• 2010

Pb(Zr,Ti)O3/BiFeO3/(PZT/BFO) multilayer thin films were coated on Pt/Ti/SiO2/Si substrates by chemical solution deposition. With increasing the annealing temperature, the dielectric and leakage current density properties of multilayered PZT/BFO/PZT thin films were improved. The current density of the PZT/BFO/PZT filmannealing at $600^{\circ}C$ was about 189.39(x10-9A/cm2) at 10V. The relative dielectric constant and the dielectric loss of the PZT/BFO/PZT thin film annealing at $600^{\circ}C$ were about 318 and 0.161%, respectively.

• 한국세라믹학회지
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• 제39권8호
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• pp.807-811
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• 2002

본 연구에서는 EUVL(Extreme Ultra-Violet Lithography) 공정에서 사용되어지는 Mo/Si 다층박막 마스크 물질의 최적화된 제조공정을 도모하기 위해 Monte Carlo법을 적용한 PVD 공정 시뮬레이터를 사용하여 Mo/Si 다층박막 증착변수에 따른 박막의 형상변화를 분석하였다. 박막의 형상은 가스압력(1∼30 mTorr), 타겟과 기판과의 거리 (1∼30 cm) 및 확산거리(1∼10 nm)에 따라 크게 변함을 알 수 있었으며 가스압력이 낮을수록, 기판과 타겟과의 거리가 멀어질수록 균일한 표면의 박막 형성이 가능할 것으로 예측되었다.

• 한국세라믹학회지
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• 제41권3호
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• pp.197-201
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• 2004

플라즈마 화학기상증착(PECVD)법을 이용하여 Si(100) 웨이퍼에 silicon oxide(SiO$_2$)와 silicon oxynitride(SiON) 후막을 SiH$_4$, $N_2$O, $N_2$가스를 혼합하여 증착하였다. RF power와 rf bias power의 변화에 따른 SiO$_2$ 막과 SiON 막의 특성변화에 대하여 고찰하였다. RF power와 rf bias power가 증가함에 따라 굴절률은 감소하는 경향을 나타내었으며, 막의 굴절률은 1552 nm에서 1.4493-1.4952까지 변화하였다. 이와 같이 rf power가 증가함에 따라 굴절률이 감소하는 이유는 oxygen의 량이 증가하고 nitrogen의 량이 감소하여 즉, O/N 비가 증가하여 굴절률이 감소하는 경향을 나타내었다.

• Composites Research
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• 제26권1호
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• pp.60-65
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• 2013

A nanolaminate consisting of alternate layers of aluminium oxide ($Al_2O_3$) (5 nm) and zirconium oxide ($ZrO_2$) (20 nm) was deposited at an optimized oxygen partial pressure of $3{\times}10^{-2}$ mbar by pulsed laser deposition. The nanolaminate film was analysed using high temperature X-ray diffraction (HTXRD) to study phase transition and thermal expansion behaviour. The surface morphology was investigated using field emission scanning electron microscopy (FE-SEM). High temperature X-ray diffraction indicated the crystallization temperature of tetragonal zirconia in the $Al_2O_3/ZrO_2$ multilayer-film was 873 K. The mean linear thermal expansion coefficient of tetragonal $ZrO_2$ was $4.7{\times}10^{-6}\;K^{-1}$ along a axis, while it was $13.68{\times}10^{-6}\;K{-1}$ along c axis in the temperature range 873-1373 K. The alumina was in amorphous nature. The FESEM studies showed the formation of uniform crystallites of zirconia with dense surface.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.166.1-166.1
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• 2014

We have controlled the graphene surface in two ways to improve the device performance of optoelectronics based on graphene transparent conductive films. We controlled multilayer graphene (MLG) work function and localized surface plasmon resonance wavelength using a silver nanoparticles formed on graphene surface. Graphene substrates were prepared using a chemical vapor deposition and transfer process. Various size of silver nanoparticles were prepared using a thermal evaporator and post annealing process on graphene surface. Silver nanoparticles were confirmed by using scanning electron microscopy (SEM). Work functions of graphene surface with various sizes of Ag nanoparticles were measured using ultraviolet photoelectron spectroscopy (UPS). The result shows that the work functions of MLG could be controlled from 4.39 eV to 4.55 eV by coating different amounts of silver nanoparticles while minimal changes in the sheet resistance and transmittance. Also the Localized surface plasmon resonance (LSPR) wavelength was investigated according to various sizes of silver nanoparticles. LSPR wavelength was measured using the absorbance spectrum, and we confirmed that the resonance wavelength could be controlled from 396nm to 425nm according to the size of silver nanoparticles on graphene surface. To confirm improvement of the device performance, we fabricated the organic solar cell based on MLG electrode. The results show that the work function and plasmon resonance wavelength could be controlled to improve the performance of optoelectronics device.

• 한국재료학회지
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• 제13권12호
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• pp.779-784
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• 2003

Nickel powders were obtained by various preparation methods, and their sintering characteristics were investigated. Nickel powders made by wet chemical process (WCP) had a higher surface area and more narrow size distribution than that of chemical vapor deposition (CVD) method. Nickel-oxide powders by the WCP method were prepared at $200^{\circ}C$ for 3 hr. The oxidation behaviour of nickel-oxide powder is similar with that of the CVD method. Nickel powders made by the WCP method showed a higher shrinkage in the range of $600^{\circ}C$∼$900^{\circ}C$ than that of commercial powder made by the CVD method. The similar results were observed on the surface microstructure of sintered bodies by SEM measurements.

• Preventive Nutrition and Food Science
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• 제21권2호
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• pp.85-89
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• 2016

Omega-3 rich fish oils are extremely labile, thus requiring control of oxidation and off flavor development. A recently proposed emulsification method, layer-by-layer (LbL) deposition, was found to be a plausible method to enhance the characteristics of bioactive ingredients, especially lipids. The present work was designed to test the possibility of enhancing the uptake and utilization of omega-3 fatty acids present in fish oil. The bioavailability of nano-emulsified fish oil was monitored in terms of intestinal absorption as well as skin permeability by using the everted intestinal sac model and Franz cell model. The skin permeability and intestinal absorption characteristics was significantly improved by LbL emulsification with lecithin/chitosan/low methoxypectin. Multilayer encapsulation along with nano-emulsification can be a useful method to deliver biologically active lipids and related components, such as fish oil. The protective effect of this tool from lipid oxidation still needs to be verified.