• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.444-450
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• 2000

We prepared Co-Cr thin film for perpendicular magnetic recording media with facing targets sputtering system(FTS system) which can deposit a high quality thin film in plasma-free state and wide range of working pressure. The effect of sputtering conditions(argon gas pressure and substrate temperature) on the magnetic and the crystallographic characteristic of Co-Cr thin film was investigated. And the variation of perpendicular coercivity with the variation of film thickness was studied. As a result we obtained the high perpendicular coercivity of 1900Oe and the good dispersion angle of c-axis($\Delta$$\theta$$_{50}$) of 5$^{\circ}$on the film thickness of 100nm for the promising recording layer of perpendicular magnetic recording media.c recording media.a.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.531-537
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• 2006

A micromachined piezoelectric microspeaker was fabricated with a highly c-axis oriented ZnO thin film on a silicon-nitride film having compressive residual stress. When it was measured 3 mm away from the microspeaker in open field, the largest sound pressure level produced by the fabricated microspeaker was about 91 dB at around 2.9 kHz for the applied voltage of $6\;V_{peak-to-peak}$. The key technologies to these successful results were as follows: (1) the usage of a wrinkled diaphragm caused by the high compressive residual stress of silicon-nitride thin film, (2) the usage of the highly c-axis oriented ZnO thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.324-327
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• 2000

ZnO(Zinc Oxide) thin films were deposited on glass substrate by Facing Targets Sputtering. Facing Targets Sputtering system can deposit thin films in plasma-free situation and change the sputtering conditions in wide range. The characteristics of ZnO thin films deposited at variation of sputtering conditions films thickness, power and substrate temperature were evaluated by XRD(x-ray diffractometer), ${\alpha}$-step (Tencor). The excellently c-axis oriented ZnO thin films were obtained at sputter pressure ImTorr, power 150W, substrate temperature 200$^{\circ}C$. In these conditions, the rocking curve of ZnO thin films deposited on glass was 3.3$^{\circ}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.901-904
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• 2000

In order to investigate the effect of deposition conditions on crystallographic properties of ZnO thin films by Facing Targets Sputtering system which can deposit thin films in plasma-free situation and change the deposition conditions in wide range. The characteristics of zinc oxide thin films on power, inter targets distance, and substrate temperature were investigated by XRD(x-ray diffractometer), alpha-step (Tencor) analyses. The excellently c-axis oriented zinc oxide thin films were obtained at sputter pressure 1mTorr, sputtering current 0.4A, substrate temperature 300$^{\circ}C$, inter target distance 100mm. In these conditions, the rocking curve of zinc oxide thin films deposited on Glass was 3.9$^{\circ}$.

• Journal of the Korean institute of surface engineering
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• v.33 no.4
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• pp.229-232
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• 2000

C-axis oriented zinc oxide thin films were deposited on glass substrate by reactive Facing Targets Sputtering (FTS) system. The characteristics of zinc oxide thin films on power, inter targets distance, and substrate temperature were investigated by XRD(x-ray diffractometer), alphastep (Tencor) analyses. The Facing Targets Sputtering system can deposit thin film in plasma-free situation and change the deposition condition in wide range. The excellently c-axis oriented zinc oxide thin films were obtained at sputter pressure 1mTorr, sputtering current 0.4A, substrate temperature $300^{\circ}C$, inter targets distance 100mm. In the conditions, the rocking curve of zinc oxide thin films deposited on ZnO/Glass was $3.9^{\circ}$.

• Journal of Sensor Science and Technology
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• v.6 no.1
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• pp.56-62
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• 1997

Using a rf-magnetron sputtering method, highly c-axis oriented La modified $PbTiO_{3}$ (PLT) ferroelectric thin films with compositions of $(Pb_{1-x}La_{x})Ti_{1-x/4}O_{3}$, where x=0.05, x=0 and x=0.15, have been obtained on (100)MgO single crystal substrate under conditions of low gas pressure. The degree of c-axis orientation of PLT films decreases with increasing gas pressure and with increasing La contant. These films were characterized by X-ray diffraction and SEM. PLT thin films of x=0.05, 0.1 and 0.15 show a low dielectric constant of 218, 246 and 361 at 1 kHz and remanent polarization(Pr) of $9{\mu}C/cm^{2}$, $8{\mu}C/cm^{2}$ and $7{\mu}C/cm^{2}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2251-2257
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• 2006

We fabricated ZnO thin film successfully by using RF magnetron sputtering and investigated its potential for being utilized as the key material of piezoelectric device with the characterization of ZnO thin film such as such as crystallinity, surface morphology, c-axis orientation, film density. In thin study, $Ar/O_2$ gas ratio is fixed 70/30, RF power 125W, working pressure 8mTorr, distance between substrate and target 70mm, but the substrate temperature is varied from room temperature to $400^{\circ}C$. The relative intensity ($I_{(002)}/I_{(100)}$) or (002) peak in ZnO thin film deposited at $300^{\circ}$ was exhibited as 94%, then its FWHM was $0.571^{\circ}C$. Also, from the surface morphology evaluated by SEM and AFM, the film deposited at $300^{\circ}C$ showed uniform particle shape and excellent surface roughness of 4.08 m. The tendency of ZnO thin film density was exhibited to be denser with increasing substrate temperature but slightly decreased at near $400^{\circ}C$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.115-120
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• 2009

The 3wt.% Al-doped zinc oxide (AZO) thin films were fabricated on Coming 1737 substrates at a fixed oxygen pressure of 200 mTorr with various substrate temperatures ($100\;{\sim}\;250^{\circ}C$) by using pulsed laser deposition in order to investigate the microstructure, optical, and electrical properties of AZO thin films. All thin films were shown to be c-axis oriented, exhibiting only a (002) diffraction peak. The AZO thin film, fabricated at 200 mTorr and $250^{\circ}C$, showed the highest (002) orientation and the full width at half maximum (FWHM) of the (002) diffraction peak was $0.44^{\circ}$. The optical transmittance in the visible region was higher than 85 %. The Burstein-Moss effect, which shifts to a high photon energy, was observed. The electrical property indicated that the highest carrier concentration ($3.48{\times}10^{20}cm^{-3}$) and the lowest resistivity ($1.65{\times}10^{-2}{\Omega}cm$) were obtained in the AZO thin film fabricated at 200 mTorr and $250^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.58-62
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• 2017

In this study, the design conditions for the Korean-style glass greenhouse structure has been reduced to achieve the most efficient use of natural light. The AGI program was simulated for the optimal conditions of daylight in a glass greenhouse. From the results of daylight simulation, the axis position of the glass greenhouse's roof was not an important factor in the daylight effects regarding illumination and uniformity. In summer, there were long periods of daylight and high illumination levels. The illumination value of daylighting increased with increasing glass transparency value, and the illumination value was greatest at 14:00 hours. At this time, the rate of light variation according to the glass transparency was 89 [lux/%]. In addition, the optimal design conditions for the glass greenhouse were established, which were a $30[^{\circ}]$ or $150[^{\circ}]$ installation angle and higher transmittance of glass.

• Polymer(Korea)
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• v.25 no.6
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• pp.803-810
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• 2001

A nonlinear optical hyperbranched polyester (PE-Azo/Hyper) was synthesized from 4-[N,N-bis(hydroxyethyl)amino-4'-formyl] azobenzene and cyanoacetic acid by a Knoevenagel polycondensation using 4-(dimethylamino) pyridine as a base. The resulting polymer was soluble in polar aprotic solvents such as N,N-dimethylformamide and 1-methyl-2-pyrrolidinone and could be processed into optical quality films by spin coating. The molecular weight was determined to be $M_w$=61,800 ($M_W/M_n{=1.86}$) by gel permeation chromatography using polystyrene as a standard. No melting point was detected by differential scanning Calorimeter, indicating that this polymer presents an amorphous state. It shows a glass transition temperature of $121^{\circ}C$. The second-order nonlinear optical coefficient $d_{33}$ of the poled polymer determined by the second harmonic generation at 1064 nm was 25.4 pm/V.