• Korean Journal of Materials Research
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• v.3 no.4
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• pp.352-360
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• 1993

A nitride layer was df'posited on the thermal oxide layer by LPCVD process. ONO(oxidenitricle oxide) capacitors with various thickness of component layer wore fabricated by wet reoxidation of the nitride with and without anrwalmg treatment and their properties were investigated. As a result of observation on the refrative index and etching behavior of the ONO fIlms, the nitride layer OF 40 A thick ness was not so dense that the bottom oxide during the reoxidation process and the capability of securing the capacitance decreased. The conduction current in the ONO multl-Iayer dielctric film was reduced as the bottom(or top) oxide layer became thicker. However, in the case of oxide with thickness more than 50A, it merely plays a factor of reduction in capacitance, and the effect of barrier for hole injection was not so much increased. Annealing of the nitride laypr bpfore reoxidation did not show a grpat effects on the refractive index and capacitance of the film, however, the annealing process increased the breakdown voltage by 2${\cdot}$V.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1857-1863
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• 2010

We present the fabrication and characterization of transparent carbon nanotube film (CNF) piezoresistors. CNFs were fabricated by vacuum filtration methods with 65?92% transmittance and patterned on Au-deposited silicon wafer by photolithography and dry etching. The patterned CNFs were transferred onto poly-dimethysiloxane (PDMS) using the weak adhesion property between the silicon wafer and the Au layer. The transferred CNFs were confirmed to be piezoresistors using the equation of concentrated-force-derived resistance change. The gauge factor of the CNFs was measured to range from 10 to 20 as the resistance of the CNFs increased with applied pressure. In polymer microelectromechanical systems, CNF piezoresistors are the promising materials because of their high sensitivity and low-temperature process.

• Textile Coloration and Finishing
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• v.27 no.2
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• pp.119-125
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• 2015

The effects of e-beam irradiation on water-repellency and washing durability of water-repellent finished chemically-recycled PET(CR-PET) fabrics were investigated. As results, more doses of e-beam irradiation damaged the fabric surface more severely. It was thought because the high densed energy was formed, where the more e-beam was converged. The contact angle measurement showed that as the dose of e-beam irradiation increased, water wettability of the CR-PET fabric increased slightly. It was thought to be due that the surface etching by e-beam irradiation let water droplet permeate into the fabric surface better. The concentration of the water-repellent finishing agent was more important factor than curing temperature as finishing parameter. It was considered because the water-repellent finishing agent used in this study got to cure sufficiently at low temperature. Consequently, e-beam irradiation improved the washing durability of water-repellent finishing on the CR-PET fabrics.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.16.1-16.1
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• 2011

$TiO_2$ is a promising material for gas sensors. To achieve high sensitivities, the material should exhibit a large surface-to-volume ratio and possess the high accessibility of the gas molecules to the surface. Accordingly, a wide variety of porous $TiO_2$ nanomaterials synthesized by wet-chemical methods have been reported for gas sensor applications. Nonetheless, achieving the large-area uniformity and comparability with well-established semiconductor production processes of the methods is still challenging. An alternative method is soft-templating which utilizes nanostructured inorganic or organic materials as sacrificial templates for the preparation of porous materials. Fabrication of macroporous $TiO_2$ films and hollow $TiO_2$ tubes by soft-templating and their gas sensing applications have been reported recently. In these porous materials composed of assemblies of individual micro/nanostructures, the form of links or necks between individual micro/nanostructures is a critical factor to determine gas sensing properties of the material. However, a systematic study to clarify the role of links between individual micro/nanostructures in gas sensing properties of a porous metal oxide matrix is thoroughly lacking. In this work, we have demonstrated a fabrication method to prepare highly-ordered, embossed $TiO_2$ films composed of anatase $TiO_2$ hollow hemispheres via soft-templating using polystyrene beads. The form of links between hollow hemispheres could be controlled by $O_2$ plasma etching on the bead templates. This approach reveals the strong correlation of gas sensitivity with the form of the links. Our experimental results highlight that not only the surface-to-volume ratio of an ensemble material composed of individual micro/nanostructures but also the links between individual micro/nanostructures play a critical role in evaluating the sensing properties of the material. In addition to this general finding, the facileness, large-scale productivity, and compatability with semiconductor production process of the proposed fabrication method promise applications of the embossed $TiO_2$ films to high-quality sensors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.603-612
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• 2000

Corrosion characteristics on the 12Cr alloy steel of turbine blade was electro-chemically investigated in 3.5wt% NaCI and 12.7wt% Na2S04 solution, respectively. Electro-chemical polarization test, Huey test and Oxalic acid etching test were previously conducted to estimate corrosion susceptibility of the material. And, using the horizontal corrosion fatigue tester, corrosion fatigue characteristics of 12Cr alloy steel in distilled water, 3.5wt% NaCI solution, and 12.7wt%(1M) Na2S04 solution were also fracture-mechanically estimated and compared their results. Parameter considered was room temperature, 60'C and 90'C. Corrosion fatigue crack length was measured by DC potential difference method.Obtained results are as follows,1) 12Cr alloy steel showed high corrosion rate in 3.5wt% NaCI solution and Na2S04 solution at high tempratue.2) Intergranular corrosion sensitivity of 12 Cr alloy was smaller than austenitic stainless steel.3) Corrosion fatigue crack growth rate in 3.5wt% NaCI and 12.7wt%(IM) Na2S04 solution is entirely higher than in the distilled water, and also increased with the temperature increase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.83-86
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• 2002

In this paper, $3^{rd}$ overtone mode energy-trapped filter using modified $PbTiO_3$ system ceramics was manufactured to apply for intermediate frequency SMD-type filter with the variations of splitted electrode size. To investigate the effects of splitted electrode size on filter characteristics of $3^{rd}$ overtone mode energy-trapped filter, ceramic wafers were fabricated by etching splitted rectangular electrode size($b{\times}d$) of b=0.4, 0.6, 0.8, 1mm, d=0.3, 0.4, 0.5mm, respectively. And then, SMD-type ceramic filter were fabricated with the size of $3.7{\times}3.1mm$. With the variations of b size, insertion loss, 3dB bandwidth and 25dB stop bandwidth showed nearly constant value, but with the variations of d size, insertion loss, 3dB bandwidth, selectivity(shape factor) decreased.⨀؀က?⨀Ⴣ?⨀਀Ⴣ?⨀ꞻꎀ̀ကꮻꎀༀ뮻ꎀ᠀Ȁ햻ꎀĀힻꎀȀ?ꎀ̀?ꎀȀꎀĀꎀĀꎀĀꎀĀꎀЀȀꎀࠀꎀഀڼꎀഀᒼꎀ؀ᮼꎀ䈀ȀȀ悼ꎀऀ檼ꎀഀȀ禼ꎀഀ螼ꎀऀȀȀ鎼ꎀഀȀꊼꎀഀ낼ꎀࠀ즼ꎀԀ쾼ꎀ܀ힼꎀ

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.105-110
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• 2011

The doping procedure in crystalline silicon solar cell fabrication usually contains oxygen injection during drive-in process and removal of phosphorous silicate glass(PSG). In this paper, we studied the effect of oxygen injection and PSG on conversion efficiency of solar cell. The mono crystalline silicon wafers with $156{\times}156mm^2$, $200{\mu}m$, $0.5-3.0{\Omega}{\cdot}cm$ and p-type were used. After etching $7{\mu}m$ of the surface to form the pyramidal structure, the P(phosphorous) was injected into silicon wafer using diffusion furnace to make the emitter layer. After then, the silicon nitride was deposited by the PECVD with 80 nm thickness and 2.1 refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$880^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Solar cells with four different types were fabricated with/without oxygen injection and PSG removal. Solar cell that injected oxygen during the drive-in process and removed PSG after doping process showed the 17.9 % conversion efficiency which is best in this study. This solar cells showed $35.5mA/cm^2$ of the current density, 632 mV of the open circuit voltage and 79.5 % of the fill factor.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.37-43
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• 2011

In this paper, the optimized doping condition of crystalline silicon solar cells with $156{\times}156\;mm^2$ area was studied. To optimize the drive-in temperature in the doping process, the other conditions except variable drive-in temperature were fixed. These conditions were obtained in previous studies. After etching$7\;{\mu}m$ of the surface to form the pyramidal structure, the silicon nitride deposited by the PECVD had 75~80nm thickness and 2 to 2.1 for a refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$850^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Drive-in temperature was changed in range of $830^{\circ}C$ to $890^{\circ}C$to obtain the sheet resistance $30{\sim}70\;{\Omega}/{\box}$ with $10\;\Omega}/{\box}$ intervals. Solar cell made in $890^{\circ}C$ as the drive-in temperature revealed 17.1% conversion efficiency which is best in this study. This solar cells showed $34.4\;mA/cm^2$ of the current density, 627 mV of the open circuit voltage and 79.3% of the fill factor.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.51-59
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• 1993

A 4${\times}10^{19}cm^{3}$ carbon-doped base AlGaAs/GaAs HBY was grown using carbontetracholoride(CCl$_4$) by atmospheric pressure MOCVD. Abruptness of emitter-base junction was characterized by SIMS(secondary ion mass spectorscopy) and the doping concentration of base layer was confirmed by DXRD(double crystal X-ray diffractometry). Mesa-type HBTs were fabricated using wet etching and lift-off technique. The base sheet resistance of R$_{sheet}$=550${\Omega}$/square was measured using TLM(transmission line model) method. The fabricated transistor achieved a collector-base junction breakdown voltage of BV$_{CBO}$=25V and a critical collector current density of J$_{O}$=40kA/cm$^2$ at V$_{CE}$=2V. The 50$\times$100$\mu$$^2$ emitter transistor showed a common emitter DC current gain of h$_{FE}$=30 at a collector current density of JS1CT=5kA/cm$^2$ and a base current ideality factor of ηS1EBT=1.4. The high frequency characterization of 5$\times$50$\mu$m$^2$ emitter transistor was carried out by on-wafer S-parameter measurement at 0.1~18.1GHz. Current gain cutoff frequency of f$_{T}$=27GHz and maximum oscillation frequency of f$_{max}$=16GHz were obtained from the measured Sparameter and device parameters of small-signal lumped-element equivalent network were extracted using Libra software. The fabricated HBT was proved to be useful to high speed and power spplications.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.19-22
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• 2013

The purpose of this study is to develop a system that can monitor the amounts of energy consumption during CVD and etching process for semiconductor manufacturing. Specifically, this system is designed to measure the $CO_2$ emission amounts quantitatively by measuring the flow rate of gas used and amount of power consumed during the processes. The processes of CVD equipment can be classified generally into processing step and cleaning step and all the two steps were monitored. In CVD and etcher equipments, various gases including Ar and $O_2$ are used, but Ar, $O_2$ and He were monitored with the use of the LCI data of Korea Environmental Industry & Technology Institute and carbon emission coefficients of EcoInvent. As a result, it was found that the carbon emission amounts of CVD equipment for Ar, $O_2$ and He were $0.030kgCO_2/min$, $4.580{\times}10^{-3}kgCO_2/min$ and $6.817{\times}10^{-4}kgCO_2/min$, respectively and those of etcher equipment for Ar and $O_2$ are $5.111{\times}10^{-3}kgCO_2/min$ and $7.172kgCO_2/min$, respectively.