• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.394-399
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• 2016

The silicon dioxide ($SiO_2$) was deposited using various gas as oxygen and nitrous oxide ($N_2O$) in nowadays. In order to improve electrical characteristics and the interface state density ($D_{it}$) in low temperature, It was deposited with carbon dioxide ($CO_2$) and silane ($SiH_4$) gas by inductively coupled plasma chemical vapor deposition (ICP-CVD). Each $D_{it}$ of $SiO_2$ using $CO_2$ and $N_2O$ gas was $1.30{\times}10^{10}cm^{-2}{\cdot}eV^{-1}$ and $3.31{\times}10^{10}cm^{-2}{\cdot}eV^{-1}$. It showed $SiO_2$ using $CO_2$ gas was about 2.55 times better than $N_2O$ gas. After 10 years when the thin film was applied to metal/insulator/semiconductor(MIS)-nonvolatile memory(NVM), MIS NVM using $SiO_2$($CO_2$) on tunneling layer had window memory of 2.16 V with 60% retention at bias voltage from +16 V to -19 V. However, MIS NVM applied $SiO_2$($N_2O$) to tunneling layer had 2.48 V with 61% retention at bias voltage from +20 V to -24 V. The results show $SiO_2$ using $CO_2$ decrease the $D_{it}$ and it improves the operating voltage.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.3
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• pp.355-362
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• 2020

The corrosion behavior of the Inconel X-750 alloy was investigated for its potential application under a Cl₂-O₂ mixed gas flow in an Ar atmosphere. The corrosion rate was found to be negligible at temperatures up to 400℃ under a flow rate of 30 mL·min^-1 Cl₂ + 170 mL·min^-1 Ar, whereas an exponential increase was observed in the corrosion rate at temperatures greater than 500℃. The suppression of the corrosion reaction due to the presence of O₂ was verified experimentally at flow rates of 30 mL·min^-1 Cl₂ (4.96 g·m^-2·h^-1), 20 mL·min^-1 Cl₂ + 10 mL·min^-1 O₂ (2.02 g·m^-2 ·h^-1), and 10 mL·min^-1 Cl₂ + 20 mL·min^-1 O₂ (1.34 g·m^-2·h^-1) under a constant Ar flow rate of 170 mL·min^-1 at 600℃ for 8 h. The surface morphology analysis results revealed that porous surfaces with tunnel-type holes were produced under the Cl₂-O₂ mixed-gas condition. Furthermore, the effects of the Cl₂ flow rate on the corrosion rate were investigated, indicating that its impact was negligible within the range of 5-30 mL·min^-1 Cl₂ at 600℃.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.35-38
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• 2002

In this paper, the characteristics of channel hot electron (CHE) injection for the write operation in a NOR-type SONOS flash memory with common source line were investigated. The thicknesses of he tunnel oxide, the memory nitride， and the blocking oxide layers for the gate insulator of the fabricated SONOS devices were $34{\AA}$, $73{\AA}$, and $34{\AA}$, respectively. The SONOS devices compared to floating gate devices have many advantages, which are a simpler cell structure, compatibility with conventional logic CMOS process and a superior scalability. For these reasons, the introduction of SONOS device has stimulated. In the conventional SONOS devices, Modified Folwer-Nordheim (MFN) tunneling and CHE injection for writing require high voltages, which are typically in the range of 9 V to 15 V. However CHE injection in our devices was achieved with the single power supply of 5 V. To demonstrate CHE injection, substrate current (Isub) and one-shot programming curve were investigated. The memory window of about 3.2 V and the write speed of $100{\mu}s$ were obtained. Also, the disturbance and drain turn-on leakage during CHE injection were not affected in the SONOS array. These results show that CHE injection can be achieved with a low voltage and single power supply, and applied for the high speed program of the SONOS memory devices.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.682-687
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• 2022

In this paper, the research results on monolithic three-dimensional integrated-circuit (M3DICs) stacked with tunneling field effect transistors (TFETs) are introduced. Unlike metal-oxide-semiconductor field-effect transistors (MOSFETs), TFETs are designed differently from the layout of symmetrical MOSFETs because the source and drain of TFET are asymmetrical. Various monolithic 3D inverter (M3D-INV) structures and layouts are possible due to the asymmetric structure, and among them, a simple inverter structure with the minimum metal layer is proposed. Using the proposed M3D-INV, this M3D logic gates such as NAND and NOR gates by sequentially stacking TFETs are proposed, respectively. The simulation results of voltage transfer characteristics of the proposed M3D logic gates are investigated using mixed-mode simulator of technology computer aided design (TCAD), and the operation of each logic circuit is verified. The cell area for each M3D logic gate is reduced by about 50% compared to one for the two-dimensional planar logic gates.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.531-536
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• 2005

Inductively coupled plasma reactive ion etching of CoTb and CoZrNb magnetic materials with the photoresist mask was performed using $Cl_2/Ar$ and $C_2F_6/Ar$ gas mixtures and characterized in terms of etch rate and etch profile. As the concentrations of $Cl_2$ and $C_2F_6$ gases increased, the etch rates of magnetic films decreased and the etch slopes became slanted. The $Cl_2/Ar$ gas was more effective in obtaining fast etch rate and steep sidewall slope than the $C_2F_6/Ar$ gas. As the coil rf power and dc bias increased, fast etch rate and steep etch slope were obtained but the redeposition on the sidewall was observed. This is due to the increase of ion and radical densities in plasma with increasing the coil rf power and the increase of incident ion energy to the substrate with increasing the dc bias voltage. By applying high density reactive ion etching to magnetic tunnel junction stack containing various magnetic films and metal oxide, steep etch slope and clean etch profile without redeposition were obtained.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.2
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• pp.119-131
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• 2020

If human skin is exposed to high concentrations of particulate matter (PM_2.5 and PM₁₀) for a long time in the outdoor environment such as subway tunnel, it will be adversely affected. In particular, fine particles can damage the skin, causing inflammation and allergic reactions. This study investigated the ability of evening primrose root (EEPR) extract to suppress the skin damages caused by the fine particles. PM was collected from a subway tunnel, where high concentrations have been reported per day over the course of a study. The EEPR had higher antioxidant activity than that of control group (62.6%). The mixture of EEPR and PM inhibited the production of nitric oxide (NO), thereby alleviating skin inflammation caused by fine particle dust. EEPR had weaker cytotoxic activity than the positive control. When cells were exposed to particulate-type dust (PM₁₀), the levels of free radicals were decreased with the increased concentrations of the extract (5, 10, 20 ㎍/mL). While at the same time more effective than positive controls. Therefore, this study proved that the Moonlight flower root extract can be used as a cosmetic material for skin by providing an effect to alleviate skin damage caused by fine particle-type dust.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.82-82
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• 2015

Industrial crystalline silicon (c-Si) solar cells with using a screen printing technology share the global market over 90% and they will continue to be the same for at least the next decade. It seems that the $2^{nd}$ generation and the $3^{rd}$ generation technologies have not yet demonstrated competitiveness in terms of performance and cost. In 2014, new world record efficiency 25.6% (Area-$143.7cm^2$, Voc-0.740V, $Jsc-41.8mA/cm^2$, FF-0.827) was announced from Panasonic and its cell structure is Back Contact $HIT^*$ c-Si solar cell. Here, amorphous silicon passivated contacts were newly applied to back contact solar cell. On the other hand, 24.9% $TOPCon^{**}$ cell was announced from Fraunhofer ISE and its key technology is an excellent passivation quality applying tunnel oxide (<2 nm) between metal and silicon or emitter and base. As a result, to realize high efficiency, high functional technologies are quite required to overcome a theoretical limitation of c-Si solar cell efficiency. In this presentation, Si solar cell technology summarized in the International Technology Roadmap for Photovoltaics ($^{***}ITRPV$ 2014) is introduced, and the present status of R&D associated with various c-Si solar cell technologies will be reviewed. In addition, national R&D projects of c-Si solar cells to be performed by Korea University are shown briefly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.54-57
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• 2002

In this study, a new programming method, to minimize the generation of Si-SiO$_2$ interface traps of scaled SONOS flash memory as a function of number of program/erase cycles has been proposed. In the proposed programming method, power supply voltage is applied to the gate, forward biased program voltage is applied to the source and the drain, while the substrate is left open, so that the program is achieved by Modified Fowler-Nordheim (MFN) tunneling of electron through the tunnel oxide over source and drain region. For the channel erase, erase voltage is applied to the gate, power supply voltage is applied to the substrate, and the source and drain are open. A single power supply operation of 3 V and a high endurance of 1${\times}$10$\^$6/ prograss/erase cycles can be realized by the proposed programming method. The asymmetric mode in which the program voltage is higher than the erase voltage, is more efficient than symmetric mode in order to minimize the degradation characteristics of scaled SONOS devices because electrical stress applied to the Si-SiO$_2$ interface is reduced by short programming time.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.116-123
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• 2016

This paper presents the fabrication and evaluation of the novel drag force type air flowmeter using MEMS technologies for the vehicle applications. To obtain the air drag force, the flowmeter utilized the curved beam structure, which was realized by the difference of residual stress between the silicon oxide layer and the silicon nitride layer. The paddle structure was applied for the maximum air drag force, and the dual-beam was adapted to prevent distortion. The basic experiments were performed in the wind tunnel, and the stable outputs were obtained. The device was applied to the internal combustion engine, and the results were compared with the HI-DS output where the convection thermal flowmeter was used as the reference sensor. The results indicated that the comparable resolutions and response times were obtained under the various engine speeds.

• Journal of Ship and Ocean Technology
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• v.8 no.1
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• pp.1-9
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• 2004

Experiments on friction drag reduction by injecting polymer (Polyethylene oxide) solution or micro-bubbles were carried out in the cavitation tunnel of KRISO. Two different drag reduction mechanisms were applied to a slender axi-symmetric body to measure the total drag reduction. And then the amount of friction drag reduction was estimated under the assumption that the reduction mechanisms were effective only to the friction drag component. As the result of the tests, polymer solution drag reduction up to 23％ of the total drag was observed and it corresponds to about 35％ of the estimated friction drag of the axi-symmetric body. This result matched reasonably well to that of the flat plate test "(Kim et al, 2003)". The normalization of the controlling parameters was tried at the end of this paper. Micro-bubble drag reduction was within 1％ of its total drag. This unexpected result was quite different from that of the flat plate case "(Kim et at, 2003)" The possible reasons were discussed in this paper.