• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.446-452
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• 2007

[ $(Pb_{1.1},La_{0.08})(Zr_{0.65}.Ti_{0.35})O_3$ ] thin films on the $Pt/Ti/SiO_2/Si$, $TiO_2(interlayer)/Pt/Ti/SiO_2/Si$ substrate were fabricated by the R.F. magnetron-sputtering method and considered their characteristics depending on $TiO_2$ interlayer. Changing the deposition conditions of $TiO_2$ interlayer, we obtained $TiO_2$ anatase single phase and rutile single phase. PLZT was deposited on these substrates and analyzed by x-ray diffraction(XRD) for there crystallinity and orientation. To investigate $PLZT-TiO_2$, $TiO_2-Pt$ interface, glow discharge spectrometer(GDS) analysis was carried out and we performed electrical measurements for dielectric properties of PLZT thin films. The PLZT thin film on $TiO_2$ anatase interlayer was found to have (110)-preferred orientation and 12.6 ${\mu}C/cm^2$ remaining polarization value.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.288-292
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• 2009

Hydrophobic/hydrophilic patterned substrates were fabricated on a glass substrate by a liquid phase deposition (LPD) method. Hydrophobic surface was obtained by modifying ZnO thin films with a rough surface using a fluoroalkyltrimethoxysilane (FAS) and hydrophilic surface was prepared by decomposing FAS on an exposed to UV light. The hexagonal ZnO rods were perpendicularly grown by LPD method on glass substrates with a ZnO seed layer. The diameter and thickness of hexagonal ZnO rods were increased as a function of increases of immersion time. The surface morphology, thickness, crystal structure, transmittance and contact angle of prepared ZnO thin films were measured by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-visible spectrophotometer (UV-vis) and contact angle measurement. Hydrophilic ZnO thin films with a contact angle of $20^{\circ}{\sim}30^{\circ}$ were changed to a hydrophobic surface with a contact angle of $145^{\circ}{\sim}161^{\circ}$ by a FAS surface treatment. Prepared hydrophobic surface was pattered by an irradiation of UV light using shadow mask with $300\;{\mu}m$ or 3 mm dot size. Finally, the hydrophobic surface exposed to UV light was changed to a hydrophilic surface.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.8-16
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• 2010

In this paper, we investigated the effects of $O_2$ fraction on the properties of Al-doped ZnO (AZO) thin films prepared by radio frequency (RF) magnetron sputtering. Hall, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) measurements revealed that the p-type conductivity was exhibited for AZO films with an $O_2$ fraction of 0.9 while the n-type conductivity was observed for films with $O_2$ fractions in range of 0 - 0.6. PL and XPS also showed that the acceptor-like defects, such as zinc vacancies and oxygen interstitials, increased in films prepared by an $O_2$ fraction of 0.9, resulting in the p-type conductivity in the films. Hall results indicated that AZO films prepared by $O_2$ fractions in range of 0 - 0.6 can be used for electrode layers in the applications of transparent thin film transistor. We concluded from the X-ray diffraction analysis that worse crystallinity with a smaller grain size as well as higher tensile stress was observed in the films prepared by a higher $O_2$ fraction, which is related to incorporation of more oxygen atoms into the films during deposition. The study of atomic force microscope suggested that the smoother surface morphology was observed in films prepared by using $O_2$ fraction, which causes the higher resistivity in those films, as evidenced by Hall measurements.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.175-179
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• 1997

bliniaturization oi microwave circuit components is an important issue with the development in the mobile communication. Capacitors, inductors anti hybrid devices of these are building blocks of electric circuits, and the fabrication of these devices using thin film technology will influence on the miniaturization of electronic devices In this paper, we report the successful fabrication of the inductors, capacitors and LC hybrid devices using a ferroelectric and a ferromagnetic oxide thin iilm. Au, stable at high temperatures in oxidizing ambient, is patterned by lift-off process, and oxide thin films are deposited by ion beam sputtering and chemical vapor deposition. These devices are characterized by a network analyzer in 0.5-15GtIz range We got the inductance of 5nH, capacitance oi 10, 000 pF and resonant frequencies of $10^{6}-10^{9}Hz$.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1208-1214
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• 2018

The one-step spin coating method is reported as an excellent thin film process because it can be easily used to fabricate high-quality methyl-ammonium lead tri-iodide ($MAPbI_3$) perovskite layers. One of the important things in the one-step spin coating method towards obtaining high-quality $MAPbI_3$ layers is the anti-solvent (AS) engineering, which consists of an one-step deposition of the $MAPbI_3$ film and dripping of the AS. The properties of the $MAPbI_3$ layer were found to be strongly influenced by the amount, dispensing speed, and spraying time of the AS solution. The $MAPbI_3$ solution was prepared by dissolving lead iodide and methyl-ammonium iodide in N,N-dimethylformamide and adding N,N-dimethyl sulfoxide. Diethyl ether (DE) was used for the AS solution. The results indicate that a $MAPbI_3$ layer appropriately sprayed with DE is beneficial for improving film quality and device efficiency because nucleation of $MAPbI_3$ layer is affected by the characteristics of DE, which affect the film's crystallinity, density, and surface morphology. The $MAPbI_3$ layer, which was optimized by using 0.7 mL of DE, a 3.03 mL/sec dispensing speed, and a 7 second time to spray after spinning showed the best efficiency of 13.74%, which was reproducible.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.105-110
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• 2000

The $\alpha$-$Fa_{2}O_{3}/SnO_{2}$ thin film gas sensor was fabricated by APCVD and heat treated. The gas sensitivity to flammable gases ($CH_4$, $H_2$, LPG) was measured. This device was to heat treatment at $400^{\circ}C$, $450^{\circ}C$, $500^{\circ}C$, $550^{\circ}C$, $600^{\circ}C$ for 2 h to enhance the gas sensitivity. The heat treated device at $500^{\circ}C$ for 2 h had the best properties and especially it shows high sensitivity to H2 gas. The sensitivity to gases was studied in the temperature range from lOoC to $300^{\circ}C$ in order to find the optimum detection temperature. In the range of detection from 500 ppm to 10,000 ppm at $175^{\circ}C$ the fabricated device showed that the gas sensitivity to $H_2$ was from 62%~76% and to $CH_4$ was from 16 %~58% and to LPG was from 8%~37 %. The sensitivity difference between heat treated device and as fabricated one was about 10 8 The long-term stability to LPG at 1,000 ppm was converged to sensitivity of 30 %.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.28-32
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• 2005

The optical properties and intrinsic stress of $Ta_{2}O_{5}$ thin films deposited by Dual ion-Beam Sputtering: (DIBS) and Single ion-Beam Sputtering (SIBS) were studied as a function of the substrate temperature and assist ion beam voltage. The refractive index showed the maximum value (n = 2.144) at $150^{circ}C$ in the SIBS process. When the substrate temperature has above $150^{circ}C$ in the SIBS process the refractive index decreased. In the DIBS process, the increase of the substrate temperature affected the increase of the refractive index at a maximum value (n = 2.1117, at $200^{circ}C$). The low temperature process $(<100^{circ}C)$ can greatly reduce residual stress with the assist ion gun, but the high temperature process was unaffected. As the assist ion beam voltage increase from 250 to 350 V the refractive index increased to 2.185. However, the refractive index was decreased at the range of 350-650 V, As the assist ion beam voltage increased, the stress of the deposited film decreased to 0.1834 GPa at 650 V.

• Korean Journal of Materials Research
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• v.2 no.5
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• pp.353-359
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• 1992

Thermal oxidation and plasma enhanced chemical vapor deposition of tantalum oxide thin films on p-type (100) Si substrates were studied to examine the dielectric nature of T$a_2O_5$ as a Al/T$a_2O_5$/p-Si capacitor. Microstructure and dielectric properties of the capacitors were investigated by XRD, AES, high frequency C-V analyzer, I-V meter and TEM. XRD analysis showed that the structure of T$a_2O_5$ films were amorphous, but the films were crystallized to hexagonal $\delta$-T$a_2O_5$ by 65$0^{\circ}C$ thermal oxidation treatment. It was found that the stoichiometry of the films was more or less close to 2 : 5. Leakage current density and relative dielectric constant of thermal oxidation T$a_2O_5$ film at 60$0^{\circ}C$ was 5.0${ imes}10^{-6}$/A/c$m^2 and 31.5, respectively. In the case of PECVD T$a_2O_5$film deposited at 0.47W/c$m^2 they were 2.5${ imes}10^{-5}$/A/$ extrm{cm}^2$ and 24.0, respectively. The morphology of the films and interfaces were investigated by TEM.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.62-70
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• 2001

The ZnSe sample grown by chemical bath deposition (CBD) method were annealed in Ar gas at $45^{\circ}C$. Using extrapolation method of X-ray diffraction pattern, it was found to have zinc blend structure whose lattice parameter $a_o$ was $5.6687\;{\AA}$. From Hall effect, the mobility was likely to be decreased by impurity scattering at temperature range from 10 K to 150 K and by lattice scattering at temperature range from 150 K to 293 K. The band gap given by the transmission edge changed from $2.700{\underline{5}}\;eV$ at 293 K to $2.873{\underline{9}}\;eV$ at 10 K. Comparing photocurrent peak position with transmission edge, we could find that photocurrent peaks due to excition electrons from valence band, ${\Gamma}_8$ and ${\Gamma}_7$ and to conduction band ${\Gamma}_6$ were observed at photocurrent spectrum. From the photocurrent spectra by illumination of polarized light on the ZnSe thin film, we have found that values of spin orbit coupling splitting ${\Delta}so$ is $0.098{\underline{1}}\;eV$. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be $0.061{\underline{2}}\;eV$ and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be $0.017{\underline{2}}\;eV$, $0.031{\underline{0}}\;eV$, respectively.

• Korean Journal of Materials Research
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• v.11 no.7
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• pp.575-579
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• 2001

GaN buffer layer and epilayer have been grown on sapphire (0001) by metal organic chemical vapor deposition (MOCVD). GaN buffer layer ranging from 26 nm to 130 nm in thickness was grown at 55$0^{\circ}C$ prior to the 4 $\mu\textrm{m}$ thick GaN epitaxial deposition at 110$0^{\circ}C$. After GaN buffer layer growth, buffer layer surface was examined by atomic force microscopy (AFM). As the thickness of GaN buffer layer was increased, surface morphology of GaN epilayer was investigated by scanning electron microscopy (SEM). Double crystal X-ray diffraction (DCXRD) and Raman spectroscopy were employed to study crystallinity of GaN epilayers. Optical properties of GaN epilayers were measured by photoluminescence (PL). The epilayer grown with a thin buffer layer had rough surface, and the epilayer grown with a thick buffer layer had mirror-like surface of epilayer. Although the stress on the latter was larger than on the former, its crystallinity was much better. These results imply that the internal free energy is decreased in case of the thick buffer layer. Decrease in internal free energy promotes the lateral growth of the GaN film, which results in the smoother surface and better crystallinity.