• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.301-304
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• 2002

We investigated the structural and electrical properties of Ce-doped Ba($Zr_{0.2}Ti_{0.8}$)$O_3$(BCZT) thin films with a mole fraction of x=0.2 and a thickness about 100 nm. BCZT films were prepared on Pt/Ti/$SiO_2$/Si substrate by a RF magnetron sputtering system. We have measured the thickness profile with Ar/$O_2$ ratio and the surface roughness. It was observed that the oxygen gas, which introduced during the film deposition, have an influence on the roughness of the film and the film roughness was reduced by annealing from 2.33 nm to 2.02 m (RMS at $500^{\circ}C$, Ar:6 scrim, $O_2$:6 sccm). We have found that annealing procedure after top electrode deposit can reduce the dissipation factor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.504-509
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• 1999

In-situ cleaning and subsequent silicon epitaxial film growth were performed in a load-locked reactor equipped with Hg-grid UV lamp and PBN heater to obtain the smooth and contaminant-free underlying surface and develop low-temperature epitaxial film growth process. The removals of organic and native oxide were investigated using UV-excited $O_2$ and $NF_{3}/H_{2}$, and the effect of the surface condition was examined on the quality of silicon epitaxial film grown at temperature as low as $750^{\circ}C$. UV-excited gas phase cleaning was found to be effective in removing the organic and native oxide successfully providing a smooth surface with RMS roughness of 0.5$\AA$ at optimal condition. Crystalline quality of epitaxial film was determined by smoothness of cleaned surface and the presence of native oxide and impurity. Crystalline defects such as dislocation loops or voids due to the surface roughness were observed by XTEM.

• Progress in Superconductivity and Cryogenics
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• v.13 no.4
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• pp.18-21
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• 2011

In this work, the yttrium oxide($Y_2O_3$) thin films as the buffer layer were prepared by the simple solution coating and reel-to-reel process on an unpolished metal tape substrate. The $Y_2O_3$ thin films were successfully synthesized by the hydrolysis of yttrium acetate. We have studied the improvement of surface roughness with the concentration of solution(0.1 M, 0.4 M, M) and the number of coatings. The planarization by solution coating process is simple in comparison with the existing polishing process, and it is eco-friendly, and has the benefits of low cost process. The thickness of $Y_2O_3$ films was increased with the $Y_2O_3$ concentration in the solution, and the surface became smoother with the number of coating cycles. Using this process, we have achieved 1.2 nm RMS roughness from a starting roughness of over 31 nm on 25 ${\mu}m^2$ area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.361-364
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• 2003

It was investigated that the structural and electrical Properties of Ce-doped Ba(Zr$_{x}$Ti$_{1-x}$ )O$_3$ (BCZT) thin films with a mole fraction of x=0.2 and a thickness about 100 nm. BCZT films were prepared on Pt/Ti/SiO$_2$/Si substrate by a RF magnetron sputtering system. We have measured the thickness profile with Ar/O$_2$ ratio and the surface roughness. It was observed that the oxygen gas, which introduced during the film deposition, have an influence on the roughness of the film and the film roughness was reduced by annealing from 2.33 nm to 2.02 nm (RMS at 500 $^{\circ}C$, Ar:6 sccm, $O_2$:6 sccm). It was found that annealing procedure after top electrode deposit can reduce the dissipation factor.

• Korean Journal of Metals and Materials
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• v.46 no.4
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• pp.217-222
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• 2008

Characteristics of etching and induced surface morphology variation by wet-etching of n-face n-type GaN were investigated using KOH solutions. It was observed that hexagonal pyramids were formed on the etched surface regardless of etching conditions. However, the size of the hexagonal pyramids was changed as the etching time and temperature increased, respectively. Initially, as the etching time and concentration of KOH solution increased, the hexagonal pyramid was observed to be dissociated into smaller pyramids. However, as the etching time increased further, the size of the hexagonal pyramids increased again, indicating that the etching of N-face n-type GaN by KOH solutions proceeded through the evolution of hexagonal pyramids, such as formation, dissociation and enlargement of pyramids. Furthermore, it was also observed that there is a correlation between the photoluminescence intensity of the etched surface and the value of root-mean-square roughness. The intensity of PL increased as the roughness value increased due to the enhancement of the extraction efficiency of the generated photons.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.4
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• pp.193-197
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• 2023

Transparent and conducting titanium (Ti) doped indium oxide (TIO) thin films were deposited on the poly-imide (PI) substrate with radio frequency magnetron sputtering and then electron irradiation was conducted on the TIO film's surface to investigate the effect electron irradiation on the crystallization and opto-electrical properties of the films. All x-ray diffraction (XRD) pattern showed two diffraction peaks of the In₂O₂ (431) and (444) planes with regardless of the electron beam irradiation energy. In the AFM analysis, the surface roughness of as deposited films was 3.29 nm, while the films electron irradiated at 700 eV, show a lower RMS roughness of 2.62 nm. In this study, the FOM of as deposited TIO films is 6.82 × 10^-3 Ω^-1, while the films electron irradiated at 500 eV show the higher FOM value of 1.0 × 10^-2 Ω^-1. Thus, it is concluded that the post-deposition electron beam irradiation at 500 eV is the one of effective methods of crystallization and enhancement of opto-electrical performance of TIO thin film deposited on the PI substrate.

• Journal of Magnetics
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• v.7 no.3
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• pp.72-79
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• 2002

Local M-H loops have been measured on the free layer of a tunneling magnetoresistance (TMR) junction using the magneto-optical Kerr effect (MOKE) system, with an optical beam size of about 2 $\mu$m diameter. Tunnel junctions were deposited using the DC magnetron sputtering method in a chamber with a base pressure of 3$\times$10$^{-9}$ Torr. The relatively irregular variations of coercive force H$_c$(∼17.5 Oe) and unidirectional anisotropy field H$_{ua}$(∼7.5 Oe) in the as-deposited sample are revealed. After $200{^{\circ}C}$ annealing, He decreases to 15 Oe but H$_{ua}$ increases to 20 Oe with smooth local variations. Two-dimensional plots of H$_c$ and H$_{ua}$ show the symmetric saddle shapes with their axes aligned with the pinned layer, irrespective of the annealing field angle. This is thought to be caused by geometric effects during deposition, together with a minor annealing effect. In addition, the variation of root mean square (RMS) surface roughness reveals it to be symmetric with respect to the center of the pinned-layer axis, with the roughness of 2.5 $\AA$ near the edge and 5.8 $\AA$ at the junction center. Comparison of surface roughness with the variation of H$_{ua}$ suggests that the H$_{ua}$ variation of the free layer is well described by dipole interactions related to surface roughness. As a whole, the reversal magnetization is not uniform over the entire junction area and the macroscopic properties are governed by the average sum of local distributions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.203-212
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• 2010

Water spray cooling has been widely used in a variety of industrial applications. The present study concentrated on quantitative measurements of the heat flux and heat transfer coefficient by water spray as it impinges on the rough surface of a hot steel plate at $900^{\circ}C$. A novel experimental technique was developed for a hightemperature heat flux gauge with a test block, cartridge heaters, and thermocouples that was used to measure the surface heat flux information on the hot steel plate for local heat flux measurements. The roles of the surface roughness on heat transfer are presented in this paper for well-characterized four rough surfaces with average rms roughness heights of $40-80{\mu}M$. The results show that the local heat transfer for rough surfaces is higher than that for a smooth surface. Heat transfer can be significantly increased by the presence of surface roughness elements, which can disrupt the thin thermal boundary layer. In addition, the heat transfer enhancement mechanism on a rough surface can be investigated by a different boiling regime.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1263-1269
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• 1999

An FBAR(Solidly Mounted Resonator) was fabricated using reflector layers which prohibit the penetration of bulk acoustic wave into substrate. The SMR consisted of top and bottom electrodes(Al films), a piezoelectric layer (ZnO film), reflector layers(W/$Si_2$ films) and Si substrate. The electrodes were deposited by dc sputtering. The piezoelectric layer and the reflector layers were deposited by rf magnetron sputtering. The control of crystallinity, microstructures and electric properties of each layer was essential for attaining the optimum FBAR characteristics. Under the best deposition conditions for FBAR devices, the ZnO films had highly c-axis preferred orientation(${\sigma}=2.17^{\circ}$), resistivity of $10^4\;{\omega}cm$, and surface roughness of 10.6 ${\AA}$. On the other hand, the surface roughness of W and $Si_2$ films was 16 ${\AA}$ and 33 ${\AA}$, respectively, and the resistivity of Al film was $5.1{\times}10^{-6}\;{\Omega}cm$. The SMR devices were fabricated by the conventional semiconductor processes. In the resonance conditions of the SMR, the series resonance frequency (fs) and the parallel resonance frequency(fp) were 1.244 GHz and 1.251 GHz, respectively and the quality factor(Q) was 1200.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.863-866
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• 2013

SiC crystal ingots were grown on 6H-SiC dual-seed crystals with different surface roughness and different seed orientation by a PVT (Physical Vapor Transport) method. 4H and 15R-SiC were grown on seed crystal with high root-mean-square (rms) value. The polytype of grown crystal on the seed crystal with lower rms value was confirmed to be 6H-SiC. On the other hand, all SiC crystals grown on seed crystals with different seed orientation were proven to be 6H-SiC. The surface roughness of seed crystals had no effect on the crystal structure of the grown crystals. However, the crystal quality of 6H-SiC single crystals grown on the on-axis seed were revealed to be slightly better than that of 6H-SiC crystal grown on the off-axis seed.