• Journal of Surface Science and Engineering
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• v.32 no.2
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• pp.83-92
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• 1999

GaN etching was performed using planar inductively coupled $Cl_2$-based plasmas and the effects of main process parameters on the characteristics of the plasmas and their relations to GaN etch rates were studied. Also, the GaN etch mechanism was investigated using a Langmuir probe and optical emission spectroscopy (OES) during the etching, and X-ray photoelectron spectroscopy (XPS) of the etched surfaces. The GaN etch rates increased with the increase of chlorine radical density and ion energy, and a vertical etch profile haying the etch rate close to 4000 $\AA$/min could be obtained. The addition of 10% Ar to $Cl_2$ gas increased the GaN etch rate and the addition of Ar (more than 20%) and HBr generally reduced the GaN etch rate. The GaN etch rate appeared to be more affected by the chemical reaction between Cl radicals and GaN compared to the physical sputtering itself under the sufficient ion bombardments to break GaN bonds.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.804-808
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• 1998

The inductively coupled plasma(ICP) etching of platinum with BCl$_3$/Cl$_2$ gas chemistry has been studied. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical binding states of the etched surface. The plasma characteristics was extracted from optical emission spectroscopy (OES) and a single Langmuir probe. In this case of Pt etching using BCl$_3$/Cl$_2$ gas chemistries, the result of OES and Langmuir probe showed the increase of Cl radicals and ion current densities in the plasmas with increasing Cl$_2$ gas ratio. At the same time, XPS results indicated that the intensities of Pt 4f decreased with increasing Cl$_2$ gas ratio. The decrease of Pt 4f intensities implies the increase of residue layer thickness on the etched Pt surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.26-29
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• 2001

SrBi$_2$Ta$_2$$O_{9}$ thin films were etched at high-density C1$_2$/CF$_{4}$/Ar in inductively coupled plasma system. The etching of SBT thin films in C1$_2$/CF$_{4}$/Ar were chemically assisted reactive ion etching. The maximum etch rate was 1300 $\AA$/min at 900W in Cl$_2$(20)/CF$_4$(20)/Ar(80). As f power increase, radicals (F, Cl) and ion(Ar) increase. The influence of plasma induced damage during etching process was investigated in terms of the surface morphology and th phase of X-ray diffraction. The chemical residue was investigated with secondary ion mass spectrometry.y.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.550-556
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• 2022

The performance of enzymatic fuel cells that convert chemical energy contained in various organic molecules such as sugar, alcohol, organic acids, and amino acids into electrical energy is greatly affected by the cathode as well as the anode. This study aimed to develop a laccase-based cathode with high performance. An enzyme composite composed of an laccase, redox mediator, and carbon nanotubes was immobilized on the surface of electrode in multiple layers, and the effect of the number of layers and the presence or absence of carbon nanotubes on electrode performance was investigated. As the number of layers of the enzyme-mediator (Lac-(PVI-Os-dCl)) on the electrode surface increased, the amount of reduction current generated at the electrode increased. The enzyme-carbon nanotube-mediator composite electrode (Lac-SWCNTs-(PVI-Os-dCl)) generated a current 1.7 times greater than that of the Lac-(PVI-Os-dCl). It was found that the largest amount of current (10.1±0.1 µA) was generated in the electrode composed of two layers of Lac-(PVI-Os-dCl) and two layers of Lac-SWCNTs-(PVI-Os-dCl) in the evaluation of electrodes with different ratio of Lac-SWCNTs-(PVI-Os-dCl) and Lac-(PVI-Os-dCl). The maximum power density of the cell using the cathode composed of a single layer of Lac-(PVI-Os-dCl) and the cell using the optimized cathode were 0.46±0.05 and 1.23±0.04 µW/cm², respectively. In this study, it was demonstrated that the performance of cathode and the enzymatic fuel cell using the same can be improved by optimizing the layers of composites composed of laccase, redox mediator, and carbon nanotubes on the electrode surface.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.43-49
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• 2023

This study reports on the preparation of sodium caseinate-cardanol (CasNa/CL)-based papers coated with different amounts of bentonite (BN) for use as a sustainable packaging material. Their chemical and morphological structures, mechanical properties, water vapor permeability, surface properties, and antioxidant activity of coated papers was assessed as a function of the BN content. The drying of the CasNa/CL coated papers led to the formation of pinholes on their surfaces owing to the presence of trapped water resulting from the difference in the drying rate between the external surface and the inside of the coated layers. Increasing the BN content reduced the pinholes on surface of CasNa/CL/BN coated papers and highly decreased the water vapor transmittance rate of the papers from 387.3±1.9 g/m²·day to 269.25±4.5 g/m²·day. Free radical scavenging assays indicated the addition of CL to the CasNa exhibited the antioxidant activity and antioxidant activity of CasNa/CL/BN did not changed as increase of BN contents. The improved water vapor barrier property and antioxidant activity of CasNa/CL/BN coated papers can be promised for various packaging applications.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.816-823
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• 1996

Chlorine containing high density plasmas are widely used to etch various materials in the microelectronic device fabrication. In this study, the characteristics of inductively coupled $Cl_2(O_2/N_2$) plasmas and their effects on the formation of silicon etching have been investigated using a Langmuir probe, quadrupole mass spectrometry(QMS), X-ray photoelectron spectroscopy(XPS), and Scanning Electron Microscopy(SEM). The addition of oxygen for chlorine plasmas reduced ion current densities and chlorine radical densities compared to the nitrogen addition by the recombination of oxygen with chlorine. Also, when silicon is etched in $Cl_2/O_2$ plasmas, etch products recombined with oxygen such as $SiCl_xO_y$ emerged. However, when nitrogen is added to chlorine, etch products recombined with nitrogen or Si-N bondings on the etched silicon surface were not found. All the silicon etch characteristics were dependent on the plasma conditions such as ion density, radical density, etc. As a result sub micron vertical silicon trench etch profiles could be effectively formed using optimized etch conditions for $Cl_2/O_2\; and \;Cl_2/N_2$ gas combinations.

• Journal of Surface Science and Engineering
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• v.42 no.6
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• pp.256-259
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• 2009

The wafer surface temperature is an important parameter in the etching process which influences the reaction probabilities of incident species, the vapor pressure of etch products, and the re-deposition of reaction products on feature surfaces. In this study, we investigated all of the effects of substrate temperature on the etch rate of $ZrO_2$ thin film and selectivity of $ZrO_2$ thin film over $SiO_2$ thin film in inductively coupled plasma as functions of $Cl_2$ addition in $BCl_3$/Ar plasma, RF power and dc-bias voltage based on the substrate temperature in range of $10^{\circ}C$ to $80^{\circ}C$. The elements on the surface were analyzed by x-ray photoelectron spectroscopy (XPS).

• Corrosion Science and Technology
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• v.18 no.6
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• pp.243-252
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• 2019

The pitting corrosion and inhibition studies of AZ31B magnesium alloy were investigated in the alkaline solution (pH12) with chloride and inhibitors. The corrosion behavior of passive film with/without Cl^- in the alkaline electrolyte were conducted by polarization curve and immersion tests in the presence of various additives (inhibitors) to clarify the inhibition efficiency of pitting corrosion at higher potential region. Critical concentration of pitting corrosion for Mg alloy was evaluated with 0.005 M NaCl in 0.01 M NaOH on the anodic polarization behavior. Critical pitting of AZ31B Mg alloy in 0.01 M NaOH is a function of chlorides; E_pit = - 1.36 - 0.2 log [Cl^-]. When the Sodium Benzoate (SB) was only used as an inhibitor, a few metastable pits developed on the Mg surface by an immersion test despite no pitting corrosion on the polarization curve meaning that adsorption of SB on the surface is insufficient protection from pitting corrosion in the presence of chloride. The role of SB and Sodium Dodecylbenzenesulfonate (SDBS) inhibitors for the Mg alloy surface in the presence of chloride was suppressed from pitting corrosion to co-adsorb on the Mg alloy surface with strong formation of passive film preventing pitting corrosion.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1983-1987
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• 2008

This study demonstrates the electrochemical conversion of the synthetic procedure of monolayer-protected clusters using a thin toluene layer over an edge plane pyrolytic graphite electrode. A thin toluene layer with a thickness of 0.31 mm was coated over the electrode and an immiscible liquid/liquid water/toluene interface was introduced. The transfer of the tetrachloroaurate ($AuCl_4^-$) ions into the toluene layer interposed between the aqueous solution and the electrode surface was electrochemically monitored. The $AuCl_4^-$ ions initially could not move through into the toluene layer, showing no reduction wave, but, in the presence of the phase transfer reagent, tetraoctylammonium bromide (TOABr), a cathodic wave at 0.23 V vs. Ag/AgCl was observed, indicating the reduction of the transferred $AuCl_4^-$ ions in the toluene layer. In the presence of dodecanethiol together with TOABr, a self-assembled monolayer was formed over the electro-deposited metallic gold surface. The E-SEM image of the surface indicates the formation of a highly porous metallic gold surface, rather than individual nanoparticles, over the EPG electrode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.114-119
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• 2000

Etch characteristics of SF6/CI2 electron cyclotron resonance (ECR) plasmas have been investigated. Surface reaction of gas plasma with polysilicon was also analysed using X-ray photoelectron spectroscopy (XPS). At the same time, the relationship between surface reaction and the etched profile of polysilicon was examined using XPS. The etch rate of polysilicon and oxide increases with increasing flow rate of SF6 in the SF6/CI2 gas mixture, and tis selectivity also increase also increase. It was also found that as increasing flow rate of SF6 in the SF6/CI2 gas mixture, the atomic% of chlorine detected at surface region decrease, but F and S contents increase. At the same time, when the mixing ratio of SF6 gas increases, the anisotropy of etched polysilicon is sharply decreased in the 0%~10% range of the SF6 mixing ratio, but is rarely varied in the range over 10%, in spite of the large variations in flow rates. It can be explained that the bonding of S-Si due to SiSx(x$\leq$2) compound formed on the etched surface suppress the formation of Si-Cl and 'or Si-F bonding in the silicon etching.