• Journal of the Korean Electrochemical Society
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• v.25 no.4
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• pp.134-153
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• 2022

Regardless of a trade-off relationship between energy density and safety, it is essential to improve both properties for future lithium secondary batteries. Especially, to improve the energy density of batteries further, not only thickness but also weight of separators including ceramic coating layers should be reduced continuously apart from the development of high-capacity electrode active materials. For this purpose, an attempt to replace conventional slurry coating methods with a deposition one has attracted much attention for securing comparable thermal stability while minimizing the thickness and weight of ceramic coating layer in the separator. This review introduces state-of-the-art technology on ceramic-coated separators (CCSs) manufactured by the deposition method. There are three representative processes to form a ceramic coating layer as follows: chemical vapor deposition (CVD), atomic layer deposition (ALD), and physical vapor deposition (PVD). Herein, we summarized the principle and advantages/disadvantages of each deposition method. Furthermore, each CCS was analyzed and compared in terms of its mechanical and thermal properties, air permeability, ionic conductivity, and electrochemical performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.3
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• pp.181-189
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• 2008

GaAs film growth process from trimethylgallium(TMGa) and tertiary-butylarsine(TBAs) using a horizontal MOCVD reactor was numerically studied to explain the experimental result that the decreasing surface reaction rate as the increasing partial pressure of group III species. Using the non-linear model based on the Langmuir isotherm which considers the adsorption and desorption of molecules, film deposition over the entire reactor scale was predicted by computational fluid dynamics (CFD) with the aid of the parameters obtained from the selective area growth (SAG) technique. CFD Results using the non-linear surface reaction model with the parameters determined from the SAG experiments predicted too high film growth rate compared to the measured values at the downstream region where the temperature was decreased abruptly. The pairs of ($k_s^n$, K) from the numerical simulations was $(2.52{\times}10K^{-6}mol/m^2/s,\;1.6{\times}10^5m^3/mol)$, whereas the experimentally determined was $(3.58{\times}10^{-5}mol/m^2/s,\;6.9{\times}10^5m^3/mol)$.

• Journal of the Korean Vacuum Society
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• v.11 no.2
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• pp.97-102
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• 2002

Highly-oriented ZnO thin films has been successfully deposited on Si(100) by metal organic chemical vapor deposition(MOCVD) at $250^{\circ}C$~$400^{\circ}C$ We report on the structural properties of ZnO thin film at various temperatures and at various ratios of the he and $O_2$ gas flow rates. The crystallinity of the thin films was improved and the surface smoothness decreased with the increase of the growth temperature. In x-ray diffraction analysis with respect to ZnO(0002) peak, the full width at half maximum (FWHM) of $0.4^{\circ}$ was achieved at $400^{\circ}C$.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.21-28
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• 2000

Refractory metals, W and Ti, and their nitrides, $W_2N$ and TiN, were investigated for using as an ohmic contact material with SiC single crystalline thin films. The possibility of nitride materials for using as a stable ohmic contact material of SiC at high temperatures was examined by considering the thermal stability depending on the heat treatment temperature, their electrical properties and protective behavior from the interdiffusion. W contact with SiC thin films, deposited by using new organosilicon precursor, bis-trimethylsilylmethane, showed the lowest resistivity, $2.17{\times}10^{-5}$Ω$\textrm{cm}^2$. On the other hand, Ti-based contact materials showed higher contact resistivity than W-based ones. The oxidation of contact materials was restricted by applying Pt thin films on those electrodes. Nitride electrodes had rather stable electrical properties and better protective behavior from interdiffusion than metal electrodes.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.563-575
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• 2006

Ti(C,N) films are synthesized by pulsed DC plasma enhanced chemical vapor deposition (PEMOCVD) using metal-organic compounds of tetrakis diethylamide titanium at $200-300^{\circ}C$. To compare plasma parameter, in this study, $H_2$ and $He/H_2$ gases are used as carrier gas. The effect of $N_2\;and\;NH_3$ gases as reactive gas is also evaluated in reduction of C content of the films. Radical formation and ionization behaviors in plasma are analyzed in-situ by optical emission spectroscopy (OES) at various pulsed bias voltages and gas species. He and $H_2$ mixture is very effective in enhancing ionization of radicals, especially for the $N_2$. Ammonia $(NH_3)$ gas also highly reduces the formation of CN radical, thereby decreasing C content of Ti(C, N) films in a great deal. The microhardness of film is obtained to be $1,250\;Hk_{0.01}\;to\;1,760\;Hk_{0.01}$ depending on gas species and bias voltage. Higher hardness can be obtained under the conditions of $H_2\;and\;N_2$ gases as well as bias voltage of 600 V. Hf(C, N) films were also obtained by pulsed DC PEMOCYB from tetrakis diethyl-amide hafnium and $N_2/He-H_2$ mixture. The depositions were carried out at temperature of below $300^{\circ}C$, total chamber pressure of 1 Torr and varying the deposition parameters. Influences of the nitrogen contents in the plasma decreased the growth rate and attributed to amorphous components, to the high carbon content of the film. In XRD analysis the domain lattice plain was (111) direction and the maximum microhardness was observed to be $2,460\;Hk_{0.025}$ for a Hf(C,N) film grown under -600 V and 0.1 flow rate of nitrogen. The optical emission spectra measured during PEMOCVD processes of Hf(C, N) film growth were also discussed. $N_2,\;N_2^+$, H, He, CH, CN radicals and metal species(Hf) were detected and CH, CN radicals that make an important role of total PEMOCVD process increased carbon content.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.12
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• pp.11-17
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• 2000

We investigated the growth of InGaN/GaN multiple quantum wells (MQWs) structures which emit blue light. The samples were grown in a low pressure metalorganic chemical vapor deposition system. We examined InGaN/GaN MQWs by varying growth temperatures and thicknesses of InGaN well and GaN barrier layers in MQWs. Especially, the thickness of GaN barrier in InGaN/GaN MQWs was found to severely affect the interfacial abruptness between InGaN well and GaN barrier layers. The higher order satellite peaks in the high resolution x-ray diffraction spectra and the high resolution cross sectional transmission electron microscope image of MQW structrues revealed that the interface between InGaN and GaN layers was very abrupt. Room-temperature photoluminescence spectra also showed a blue emission from InGaN/GaN MQWs at the wavelength of 463.5nm with a narrow full width at half maximum of 72.6meV.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.217-223
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• 2010

We grew multi-stacked InAs/$In_{0.1}Ga_{0.9}As$ DWELL (dot-in-a-well) structure by metal organic chemical vapor deposition and investigated optical properties by photoluminescence and I-V characteristics by dark current measurement. When stacking InAs quantum dots (QDs) with same growth parameter, the size and density of QDs were changed, resulting in the bimodal emission peak. By decreasing the flow rate of TMIn, we achieved the uniform multi-stacked QD structure which had the single emission peak and high PL intensity. As the growth temperature of n-type GaAs top contact layer (TCL) is above $600^{\circ}C$, the PL intensity severely decreased and dark current level increased. At bias of 0.5 V, the activation energy for temperature dependence of dark current decreased from 106 meV to 48 meV with increasing the growth temperature of n-type GaAs TCL from 580 to $650^{\circ}C$. This suggest that the thermal escape of bounded electrons and non-radiative transition become dominant due to the thermal inter-diffusion at the interface between InAs QDs and $In_{0.1}Ga_{0.9}As$ well layer.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.187-194
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• 1998

InGaAsP epitaxial layers lattice matched to InP were grown at 600 and $620^{\circ}C$ by low pressure metalorganic chemical vapor deposition. Solid phase composition of group III was controlled by the diffusion flux gas phase to the reachion surface. For the case of group V, the difference of As and P vapor pressure and pyrolysis efficiency of $PH_3$and $AsH_3$ mainly determined their in corporation into solid. An abnormal behavior of peak energy shift was observed below 75K in temperature variant photoluminescence study. This abnormal behavior was explained by the difference in order of ordering which makes spatial variation of energy gap in InGaAsP layer and this explanation was supported by the analyses of transmission electron microscopy and transmission spectroscopy.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.282-289
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• 2000

$PbTiO_3$ films were fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition(ECR-PECVD). Deposition characteristics of $PbTiO_3$films on $RuO_2$ and Pt substrates were investigated with varying the flow rate of metalorganic source and substrate temperature. The residence time of Pb-oxide molecules in much longer on $RuO_2$ than on Pt substrate, while the perovskite nucleation is more difficult on $RuO_2$ than on Pt substrate. Therefore, the process conditions to obtain the single perovskite $PbTiO_3$ phase are more restricted on $RuO_2$ than on Pt substrates. An introduction of Ti-oxide seed layer increases perovskite nucleation density and thus enlarges the process window to obtain the single perovkite phase. The introduction of Ti-oxide seed layer make the PZT film that Ti-components of $PbTiO_3$ are partially substituted with Zr atoms have single perovskite phase for the wide range of Zr/(Zr+Ti) concentration ratios.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1128-1132
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• 2002

$ReMnO_3$(Re:Y, Ho, Er) thin films were prepared by MOCVD method available to non-volatile memory device with MFS-FET structure. $ReMnO_3$ thin films were deposited on the Si(100) substrate at 700${\circ}C$ for 2h. When the films were post-annealed at 900${\circ}C$ for 1h in air, the single phase of hexagonal $ReMnO_3$ thin films were detected. Ferroelectric properties of $ReMnO_3$ thin films were dependent on the degree of c-axis orientation in the single phase of hexagonal structure and remnant polarization (Pr) of $YMnO_3$ thin films with high degree of c-axis orientation was 105 nC/$cm^2$. Leakage current density was dependent on the grain size of microstructure and that of $YMnO_3$ thin films with grain size of 100∼150 nm was $10^{-8}$ A/$cm^2$ at applied voltage of 0.5 V.