• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.3
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• pp.1-6
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• 2011

Low-power logic gates, i.e. inverter, NAND, and NOR, are proposed employing only n-channel oxide thin film transistors (TFTs). The proposed circuits were designed to prevent the pull-up and pull-down switches from being turned on simultaneously by using asymmetric feed-through and bootstrapping, thereby exhibited same output voltage swing as the input signal and no static current. The inverter is composed of 5 TFTs and 2 capacitors. The NAND and the NOR gates consist of 10 TFTs and 4 capacitors respectively. The operations of the logic gates were confirmed successfully by SPICE simulation using oxide TFT model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.44-47
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• 1997

In spite of the addtion of Zn, a high quality of Zn-doped GaN film were prepared. The growth rates of Zn-doped GaN films were varied from 0.14${\mu}{\textrm}{m}$/min to 0.05${\mu}{\textrm}{m}$/min according to the amount of Zn incorporated, The smallest value of the FWHM of x-ray rocking curve was 407 arcsec. The Zn-related Photoluminescence emission peaks which occurred at 2.927 and 2.824 eV shifted toward the low energy region by increasing Zn partial pressures. It was compared between the intensities of D-A pair (3.259eV) and that of the exciton bound to acceptor band(E$_{x-A}$=3.449eV).).

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1646-1648
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• 2000

This paper investigated structural and electrical properties of $Y_{2}O_3$ as a buffer layer of sin91r transistor FRAM (ferroelectric RAM). $Y_{2}O_3$ buffer layers were deposited at a low substrate temperature below 400$^{\circ}C$ and then RTA (rapid thermal anneal) treated. Investigated parameters are substrate temperature, $O_2$ partial pressure, post- annealing temperature, and suppression of interfacial $SiO_2$ layer generation. for a well-fabricated sample, we achieved that leakage current density ($J_{leak}$) in the order of $10^{-7}A/cm2$, breakdown electric field ($E_{br}$) about 2 MV/cm for $Y_{2}O_3$ film. Capacitance versus voltage analysis illustrated dielectric constants of 7.47. We successfully achieved an interface state density of $Y_{2}O_3$/Si as low as $8.72{\times}10^{10}cm^{-2}eV^{-1}$. The low interface states were obtained from very low lattice mismatch less than 1.75%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.47-50
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• 2000

This paper investigated structural and electrical properties of $Y_2$ $O_3$ as a buffer layer of single transistor FRAM (ferroelectric RAM). $Y_2$ $O_3$ buffer layers were deposited at a low substrate temperature below 40$0^{\circ}C$ and then RTA (rapid thermal anneal) treated. Investigated parameters are substrate temperature, $O_2$ partial pressure, post-annealing temperature, and suppression of interfacial $SiO_2$ layer generation. For a well-fabricated sample, we achieved that leakage current density ( $J_{leak}$) in the order of 10$^{-7}$ A/$\textrm{cm}^2$, breakdown electric field ( $E_{br}$ ) about 2 MV/cm for $Y_2$ $O_3$ film. Capacitance versus voltage analysis illustrated dielectric constants of 7.47. We successfully achieved an interface state density of $Y_2$ $O_3$/Si as low as 8.72x1010 c $m^{-2}$ e $V^{-1}$ . The low interface states were obtained from very low lattice mismatch less than 1.75%.

• Journal of the Korean institute of surface engineering
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• v.36 no.1
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• pp.27-33
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• 2003

Pulsed magnetron sputtering of graphite target was employed for deposition of diamond-like carbon (DLC) films. Time-resolved probe measurements of magnetron discharge plasma have been performed. It was shown that the pulsed magnetron discharge plasma density ($∼10^{17}$ $m^{-3}$ ) is close to that of vacuum arc cathode sputtering of graphite. Raman spectroscopy was sed to examine DLC films produced at low ( $U_{sub}$ / < 1 kV) pulsed bias voltages applied to the substrate. It has been shown that maximum content of diamond-like carbon in the coating (50-60%) is achieved at energy per deposited carbon atom of $E_{c}$ =100 eV. In spite of rather high percentage of $sp^3$-bonded carbon atoms and good scratch-resistance, the films showed poor adhesion because of absence of ion mixing between the film and the substrates. Electric breakdowns occurring during the deposition of the insulating DLC film also thought to decrease its adhesion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.743-747
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• 2007

There has been steady effect for the development of the electron-beam lithography technologies for the circuit patterning of the future semiconductor devices. In this study, we have performed a Monte-Carlo simulation whore $1{\times}10^4$ electrons with various kinetic energies (100eV, 300eV, 500eV, 700eV, and 1000eV) were shot into polymethyl methacrylate(PMMA) resist of 100-nm thickness. The penetration depth of each electron beam in the resist layer were analyzed using Gaussian analysis method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.11
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• pp.969-973
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• 2009

In this study, the electrical and optical properties of $(SiO_2)_x(ZnO)_{100-x}$ (SZO) films prepared on the coming 7059 glass substrates by using rf-magnetron sputtering method are investigated. The deposition rate becomes maximum near 3 wt.% and gradually decreases when the $SiO_2$ content further increases. The growth rates of the SZO film with $SiO_2$ content of 3 wt.% is $4\;{\AA}/s$. We found that the average transmittance of all films is over 80% in the wavelength range above 500 nm. The optical band gap were decreased from 3.52 to 3.33 eV as an increase the deposition thickness. X-ray diffraction patterns showed that the film with a relatively low $SiO_2$ content (< 4 wt.%) is amorphous. SZO film with the $SiO_2$ contents of 2 wt.% showed the resistivity of about $3.8{\times}10^{-3}\;{\Omega}{\cdot}cm$. The sheet resistance decreases with increasing the heat treatment temperature.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.340-351
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• 1995

Electrical, physical and optical properties of Aluminum(Al), Copper(Cu) thin films were investigated in order to establish the optimum sputtering parameters in Liquid Crystal Display (LCD) panel applications. DC-magnetron sputtered film on coming 7059 samples were fabricated with variations of deposition power densities, deposition pressures and substrate temperatures. Low resistivity films(AI;2.80 .mu..ohm.-cm, Cu:1.84 .mu..ohm-cm),which lower than the reported values, were obtained under sputtering parameters of power density(250W), substrate temperature(450-530.deg. C) and 5*10$\^$-3/ Torr deposition pressure. Expected columnar growth and stable grain growth of both films was observed through the Scanning Electron Microscope(SEM) micrographs. Dependency of the applicable defect-free film density upon depositon power and temperature was also characterized. Not too noticable variations in X-ray diffraction patterns were remarked under the alterations of sputtering parameters. High optical reflectivities of Al, Cu films, approximately 70-90 %, showed high degree of surface flatness.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.109-126
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• 2013

Surface modification by low-pressure ammonia ($NH_3$) plasma on commercial thin-film composite (TFC) membranes was investigated in this study. Surface hydrophilicity, total surface free energy, ion exchange capacity (IEC) and zeta (${\zeta}$)-potentials were determined for the TFC membranes. Qualitative and quantitative analyses of the membrane surface chemistry were conducted by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy. Results showed that the $NH_3$ plasma treatment increased the surface hydrophilicity, in particular at a plasma treatment time longer than 5 min at 50 W of plasma power. Total surface free energy was influenced by the basic polar components introduced by the $NH_3$ plasma, and isoelectric point (IEP) was shifted to higher pH region after the modification. A ten (10) min $NH_3$ plasma treatment at 90 W was found to be adequate for the TFC membrane modification, resulting in a membrane with better characteristics than the TFC membranes without the modification for water treatment. The thin-film chemistry (i.e., fully-aromatic and semi-aromatic nature in the interfacial polymerization) influenced the initial stage of plasma modification.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.276-276
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• 2014

High-performance, fully-transparent, and top-gated oxide thin-film transistor (TFT) was successfully fabricated with Ta2O5 high-k gate dielectric on a glass substrate. Through a self-passivation with the gate dielectric and top electrode, the top-gated oxide TFT was not affected from H2O and O2 causing the electrical instability. Heat-treated InSnO (ITO) was used as the top and source/drain electrode with a low resistance and a transparent property in visible region. A InGaZnO (IGZO) thin-film was used as a active channel with a broad optical bandgap of 3.72 eV and transparent property. In addition, using a X-ray diffraction, amorphous phase of IGZO thin-film was observed until it was heat-treated at 500 oC. The fabricated device was demonstrated that an applied electric field efficiently controlled electron transfer in the IGZO active channel using the Ta2O5 gate dielectric. With the transparent ITO electrodes and IGZO active channel, the fabricated oxide TFT on a glass substrate showed optical transparency and high carrier mobility. These results expected that the top-gated oxide TFT with the high-k gate dielectric accelerates the realization of presence of fully-transparent electronics.