• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.67-70
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• 2001

$SrBi_2Ta_2O_9$ thin films were etched at high-density $Cl_2/CF_4/Ar$ in inductively coupled plasma system. The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy and secondary ion mass spectrometry. The etching of SBT thin films in $Cl_2/CF_4/Ar$ were chemically assisted reactive ion etching. The maximum etch rate was 1060 Am /min in $Cl_2$(20)/CF_4(20)/Ar(80). The small addition of $Cl_2$ into $CF_4$(20)/Ar(80) plasma will decrease the fluorine radicals and the increase CI radical. The etch profile of SBT thin films in $Cl_2/CF_4/Ar$ plasma is steeper than in $CF_4$/Ar plasma.Ā저會Ā저ﶖ⨀⡌ឫഀĀ᐀會Ā᐀㡆ﶖ⨀쁌ឫഀĀ᐀會Ā᐀遆ﶖ⨀郞ග堂瀀ꀏ會Āﶖ⨀〲岒ऀĀ᐀會Ā᐀䁇ﶖ⨀젲岒Ā㰀會Ā㰀顇ﶖ⨀끩Ā㈀會Ā㈀ﶖ⨀䡪Ā᐀會Ā᐀䡈ﶖ⨀Ā᐀會Ā᐀ꁈﶖ⨀硫Ā저會Ā저ﶖ⨀샟ගကĀ저會Ā저偉ﶖ⨀栰岒ఀĀ저會Ā저ꡉﶖ⨀1岒Ā저會Ā저Jﶖ⨀惝ග؀Ā؀會Ā؀塊ﶖ⨀ග㼀Ā切會Ā切끊ﶖ⨀⣟ගఀĀ搀會Ā搀ࡋﶖ⨀큭킢Ā저會Ā저

• Progress in Superconductivity
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• v.10 no.2
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• pp.87-91
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• 2009

Fluorine-doped $SmFeAsO_{1-x}F_x$ single crystals with the nominal value of x=0.2 were grown at $1350-1450^{\circ}C$ under the pressure of 3.3 GPa by using the self-flux method. Plate-shaped single crystals in the range of a few-150 ${\mu}m$ in their lateral size were obtained. The detailed crystal structure was analyzed by using the x-ray diffractometry. Superconducting transition temperature, determined by the resistive transition, of a single crystal was about 49 K with a narrow resistive transition width of ${\sim}1$ K. A relatively sharp transition, a low residual resistivity, and a large residual resistivity ratio compared with those reported for $REFeAsO_{1-x}F_x$(RE=Sm, Nd) single crystals indicate the high quality of our single crystals.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.42.2-42.2
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• 2011

$TiO_2$ films were modified by adding a glass frit as a light scattering particle and applied to an anode electrode in dye-sensitized solar cells (DSSCs) to enhance the adhesion between $TiO_2$ and fluorine doped transparent oxide (FTO). Low melting point glass frits at contents of (3 to 7wt%) were added to the nano crystalline $TiO_2$ films. The light scattering properties, photovoltaic properties and microstructures of the photo electrodes were examined to determine the role of the low glass transition temperature ($T_g$) glass frit. Electrochemical impedance spectroscopy, Brunauer-Emmett-Teller method and scratch test were conducted to support the results. The DSSC with the $TiO_2$ film containing 3wt% low Tg glass frit showed optimal performance (5.1%, energy conversion efficiency) compared to the $TiO_2$-based one. The photocurrent density slightly decreased by adding 3wt% of the frit due to its large size and non conductivity. However, the decrease of current density followed by the decrease of electron transfer due to the large frit in $TiO_2$ electrode was compensated by the scattering effect, high surface area and reduced the electron transfer impedance at the electrolyte-dye-$TiO_2$ interface. The stability of the photo electrodes was improved by the frit, which chemically promoted the sintering of $TiO_2$ at relatively low temperature ($450^{\circ}C$).

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.162-167
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• 1998

$SiO_xF_y$ optical thin films of lower refractive indices than glass substrates were fabricated by the CF$_4$ ion beam assisted deposition method and the optical, structural and chemical properties of them were investigated. Refractive index of $SiO_xF_y$ films was varied from 1.455 to 1.394 by decreasing the anode voltage or from 1.462 to 1.430 by increasing the current density of end-Hall ion source. FT-IR and XPS analyses show that as the F concentration increases, the Si-O bond at $1080m^{-1}$ shifts to higher wavenumber, the OH bonds are reduced drastically, and the fluorine atoms at the air-film interface are desorbed out by reacting with $H_2O$ in the atmosphere. $SiO_xF_y$ thin films are amorphous by the XRD analysis and have the compressive stress below 0.3 GPa. As an application of $SiO_xF_y$ thin films a two-layer antireflection coating was fabricated using a $SiO_xF_y$ film as a low refractive index layer and a Si film as an absorbing one.

• Membrane Journal
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• v.20 no.2
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• pp.106-112
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• 2010

This study deals with the surface fluorination of poly(phenylene oxide) (PPO) with the direct contact of 100 ppm fluorine gas. To characterize the surface fluorinated membranes, the contac angle measurement, X-ray photoelectron microscopy analysis and the gas permeation experiments were performed. As the fluorination time increases, the hydrophobicity of membrane surfaces is increased by the surface characterization. In general, as expected, the overall gas permeability was reduced. Typically, the permeability reduction of 33% for nitrogen, 23% for oxygen and 3% for carbon dioxide were observed when the membranes were exposed in 100 ppm environment for 60 min., meanwhile the selectivity was increased from 3.92 to 4.47 for $O_2/N_2$ and 18.09 to 25.4 for $O_2/N_2$, respectively.

• Journal of Electrochemical Science and Technology
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• v.2 no.2
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• pp.110-115
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• 2011

The effect of $TiO_2$ nanotube (TNT) and nanoparticle (TNP) composite photoelectrode and the role of TNT to enhance the photo conversion efficiency in dye-sensitized solar cell (DSSC) have investigated in this study. Results demonstrated that the increase of the TNT content (1-15 %) into the electron collecting TNP film increases the open-circuit potential ($V_{oc}$) and short circuit current density ($J_{sc}$). Based on the impedance analysis, the increased $V_{oc}$ was attributed to the suppressed recombination between electrode and electrolyte or dye. Photochemical analysis revealed that the increased Jsc with the increased TNT content was due to the scattering effect and the reduced electron diffusion path of TNT. The highest $J_{sc}$ (12.6 mA/$cm^2$), Voc (711 mV) and conversion efficiency (5.9%) were obtained in the composite photoelectrode with 15% TNT. However, $J_{sc}$ and $V_{oc}$ was decreased for the case of 20% TNT, which results from the significant reduction of adsorbed dye amount and the poor attachment of the film on the fluorine-doped tin oxide (FTO). Therefore, application of this composite photoelectrode is expected to be a promising approach to improve the energy conversion efficiency of DSSC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.297-305
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• 2000

It is observed that the initial properties and degradation characteristics on plasma of n/p-MOSFET with polycide and poly-Si as different gate materials under F-N stress and hot electron stress are affected by metal AR(Antenna Ratio) during plasma process. Compared to that of MOS devices with poly-Si gate material, reliability properties on plasma of MOS devices with polycide gate material are improved. This can be explained by that fluorine of tungsten polycide process diffuses through poly-Si into gate oxide and results in additional oxide thickness. The fact that MOS devices with polycide gate material can reduce damages of plasma process shows possibility that polycide gate material can be used as gate material for next generation MOS devices.

• Transactions on Electrical and Electronic Materials
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• v.11 no.3
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• pp.120-125
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• 2010

For the fabrication of PMOS and integrated semiconductor devices, B, $BF_2$ and dual elements with B and $BF_2$ can be implanted in silicon. 15 keV B ions were implanted in silicon at $7^{\circ}$ wafer tilt and a dose of $3.0{\times}10^{16}\;cm^{-2}$. 67 keV $BF_2$ ions were implanted in silicon at $7^{\circ}$ wafer tilt and a dose of $3.0{\times}10^{15}\;cm^{-2}$. For dual implantations, 67 keV $BF_2$ and 15keV B were carried out with two implantations with dose of $1.5{\times}10^{15}\;cm^{-2}$ instead of $3.0{\times}10^{15}\;cm^{-2}$, respectively. For the electrical activation, the implanted samples were annealed with rapid thermal annealing at $1,050^{\circ}C$ for 30 seconds. The implanted profiles were characterized by using secondary ion mass spectrometry in order to measure profiles. The implanted and annealed results show that concentration profiles for the ${BF_2}^+$ implant are shallower than those for a single $B^+$ and dual ($B^+$ and ${BF_2}^+$) implants in silicon. This effect was caused by the presence of fluorine which traps interstitial silicon and ${BF_2}^+$ implants have lower diffusion effect than a single and dual implantation cases. For the fabricated diodes, current-voltage (I-V) and capacitance-voltage (C-V) were also measured with HP curve tracer and C-V plotter. Electrical measurements showed that the dual implant had the best result in comparison with the other two cases for the turn on voltage characteristics.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.5
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• pp.1-7
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• 2002

Deep sub-micron bulk CMOS circuits require gate electrode materials such as metal silicide and titanium silicide for gate oxides. Many authors have conducted research to improve the quality of the sub-micron gate oxide. However, few have reported on the electrical quality and reliability of an ultra-thin gate. In this paper, we will recommend a novel shallow trench isolation structure and a two-step TiS $i_2$ formation process to improve the corner metal oxide semiconductor field-effect transistor (MOSFET) for sub-0.1${\mu}{\textrm}{m}$ VLSI devices. Differently from using normal LOCOS technology, deep sub-micron CMOS devices using the novel shallow trench isolation (STI) technology have unique "inverse narrow-channel effects" when the channel width of the device is scaled down. The titanium silicide process has problems because fluorine contamination caused by the gate sidewall etching inhibits the silicide reaction and accelerates agglomeration. To resolve these Problems, we developed a novel two-step deposited silicide process. The key point of this process is the deposition and subsequent removal of titanium before the titanium silicide process. It was found by using focused ion beam transmission electron microscopy that the STI structure improved the narrow channel effect and reduced the junction leakage current and threshold voltage at the edge of the channel. In terms of transistor characteristics, we also obtained a low gate voltage variation and a low trap density, saturation current, some more to be large transconductance at the channel for sub-0.1${\mu}{\textrm}{m}$ VLSI devices.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.469-474
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• 2015

In ultrasonic spray pyrolysis deposition, a precursor solution is evaporated by an ultrasonic atomizer, then gas-carried into a furnace where the solute is separated from the water vapor. After condensation, polymerization, and nucleation, the solute oxide forms a thin film. To improve the deposition efficiency, the ultrasonic atomizer was studied to optimize the evaporated gas flow. The vat cover was redesigned, using three versions with different inlet factors being tested through a computational fluid dynamic analysis as well as a water evaporation experiment. The atomization rate with a hemispherical cover with a $30^{\circ}$ inlet was found to be 2.4 times higher than that with the original. This improvement was verified with fluorine-doped tin oxide spray pyrolysis deposition. The film obtained with the modified vat cover was 2.4 times thicker than that obtained with the original vat cover.