• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.245-249
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• 2004

Transparent materials such as fused silica are important materials in optical and optoelectronics field because of its outstanding properties, such as transparency in a wide wavelength range, strong damage resistance for laser irradiation, and high thermal and chemical stability. However, these properties make it difficult to micromachine silica in micro-sized quantities. In this study, we fabricated a micro patterns on the surface of fused silica plate using laser induced wet etching. KrF excimer laser was used as a light source. There were no burrs and micro cracks on the etched surface of fused silica and the flatness of the etched surface was fairly good. We investigated the influence of etchant upon the etch rate and quality in laser induced wet etching. Pyrene-acetone, toluene, and pyrene-toluene solution were used as etchant. In the side of etch rate, toluene and pyrene-toluene solution were better than pyrene-acetone solution.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.496-500
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to significantly impact terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (RIE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi-Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7% efficiency of mono-crystalline silicon solar cell and 10.2% multi-crystalline silicon solar cell.

• Journal of the Korean institute of surface engineering
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• v.42 no.4
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• pp.169-172
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• 2009

We investigated the dry-etching mechanism of the TiN thin film using a $Cl_2$/Ar inductively coupled plasma system. To understand the effect of the $Cl_2$/Ar gas mixing ratio, we etched the TiN thin film by varying $Cl_2$/Ar gas mixing ratio. When the gas mixing ratio was 100% $Cl_2$, the highest etch rate was obtained. The chemical reaction on the surface was investigated with X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) was used to examine etched profiles of the TiN thin film.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4620-4624
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• 2022

Several cadmium zinc telluride (CZT) crystals were fabricated into radiation detectors using methods that included slicing, dicing, lapping, polishing, and chemical etching. A wet passivation with sodium hypochlorite (NaOCl) was then carried out on the Br-etched detectors. The Te-rich layer on the CZT surface was successfully compensated to the Te oxide layer, which was analyzed with X-ray photoelectron spectroscopy data of both a Br-etched crystal and a passivated CZT crystals. We confirmed that passivation with NaOCl improved the transport property by analyzing the mobility-lifetime product and surface recombination velocity. The electrical and spectroscopic properties of large volume detectors were compared before and after passivation, and then the detectors were observed for a month. Both bar and quasi-hemispherical detectors show an enhancement in performance after passivation. Thus, we could identify the effect of NaOCl passivation on large volume CZT detectors.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.423-427
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• 2013

PURPOSE. This study evaluated the bond strength between porcelain denture teeth (Bioblend 43D) and four different polymerized denture resins (Lucitone 199, Palapress, Acron MC, Triad) with and without a bonding agent and after four different types of surface treatment (polished, HF etched, sandblasted, air-abraded). MATERIALS AND METHODS. Central incisor porcelain denture teeth were divided into 32 groups of 5 each. Tensile bond strength (MPa) was determined using a testing machine at crosshead speed of 0.5 mm/min. Mean and standard deviation are listed. Data were analyzed by two-way ANOVA. Means were compared by Tukey-Kramer intervals at 0.05 significance level. RESULTS. All surface treatment increased bond strength compared to polished surface and the highest bond strength was found with Palapress resin with etched porcelain surface (8.1 MPa). Bonding agent improved the bond strength of all denture resins to porcelain teeth. Superior bonding was found with Palapress and air-abraded porcelain (39 MPa). CONCLUSION. Resins with different curing methods affect the bond strength of porcelain teeth to denture bases. Superior bonding was found with auto-polymerized resin (Palapress). Application of ceramic primer and bonding agent to porcelain teeth with and without surface treatment will improve the bond strength of all denture resins to porcelain teeth.

• Journal of IKEEE
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• v.23 no.2
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• pp.534-537
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• 2019

The optical loss is caused by reflection on the surface of the solar cell, without being absorbed inside the solar cell. Research is actively being conducted to reduce optical loss due to such reflection of light and to improve conversion efficiency of solar cells. In this paper, the surface of the FTO glass substrate was wet etched, and the structural characteristics of the tough surface were evaluated. In addition, optical properties on the surface were analyzed, etched using spectrometer. When light was introduced to a rough surface formed by etching, it was confirmed that the multiple reflections reduced the amount of light reflection from the surface, thereby increaseing the amount of light penetrating the glass substrate.

• Korean Journal of Metals and Materials
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• v.47 no.11
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• pp.748-753
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• 2009

The surface morphology and the surface roughness of n-type SiC induced by wet-treatment using 45% KOH and buffered oxide etchant (BOE-1HF : $6H_2O$) were investigated by atomic force microscopy (AFM). While Si-face of SiC could be etched by alkali solutions such as KOH, acidic solutions such as BOE were hardly able to etch SiC. When the rough SiC samples were used, the surface roughness of etched sample was decreased after wet-treatment regardless of etchant, due to the planarization the of surface by widening of scratches formed by mechanical polishing. It was observed that the initial etching was affected by the energetically unstable sites, such as dangling bond and steps. However, when a relatively smooth sample was used, the surface roughness was rapidly increased after treatment at $180^{\circ}C$ for 1 hr and at room temperature for 4 hr by using KOH solution, resulting from the nano-sized structures such as pores and bumps. This indicates that porous SiC surface can be achieved by using purely chemical treatment.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.184-193
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• 2023

This study investigates the effects of a carbon fiber layer formed on the surface of an etched aluminum current collector on the electrochemical properties of the activated carbon electrodes for an electric double layer capacitor. A particle size analyzer, field-emission SEM, and nitrogen adsorption/desorption isotherm analyzer are employed to analyze the structure of the carbon fiber layer. The electric and electrochemical properties of the activated carbon electrodes using a carbon fiber layer are evaluated using an electrode resistance meter and a charge-discharge tester, respectively. To uniformly coat the surface with carbon fiber, we applied a planetary mill process, adjusted the particle size, and prepared the carbon paste by dispersing in a binder. Subsequently, the carbon paste was coated on the surface of the etched aluminum current collector to form the carbon under layer, after which an activated carbon slurry was coated to form the electrodes. Based on the results, the interface resistance of the EDLC cell made of the current collector with the carbon fiber layer was reduced compared to the cell using the pristine current collector. The interfacial resistance decreased from 0.0143 Ω·cm² to a maximum of 0.0077 Ω·cm². And degradation reactions of the activated carbon electrodes are suppressed in the 3.3 V floating test. We infer that it is because the improved electric network of the carbon fiber layer coated on the current collector surface enhanced the electron collection and interfacial diffusion while protecting the surface of the cathode etched aluminum; thereby suppressing the formation of Al-F compounds.

• Journal of the Korean institute of surface engineering
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• v.46 no.1
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• pp.22-28
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• 2013

$WS_2$ particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to improve cutting efficiency. It was found in previous works that the added $WS_2$ lubricant could reduce remarkably the momentary energy consumption during dicing tests but increased wear rate slightly owing to weak bonding between lubricant particles and bond metals. In the present work, the surface of $WS_2$ lubricant particles were etched for activating the surface of $WS_2$ particles that provide even distribution of particles during powder mixing process and improvement of wetting at the interfaces between $WS_2$ particles and molten Cu/Sn bond metals during pressurized sintering so that could provide the improved strength of micro-blades and result in extended life. Chipping behavior of workpiece with the types of micro-blades including $WS_2$ were compared because it is important in semiconductor and micro-packaging industries to control average roughness and straightness of sliced surface which is closely related with quality.

• Journal of Oral Medicine and Pain
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• v.25 no.1
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• pp.129-144
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• 2000

The purpose of this study was to examine dentin surface changes of extracted sound third molar specimens which were etched with 10% maleic acid and irradiated at $7-140J/cm^2$ with $CO_2$ and at $156-280J/cm^2$ with Nd:YAG laser. The results were as follows. 1. Dentin surfaces etched with 10% maleic acid and then irradiated at below of $42J/cm^2$ with $CO_2$ laser showed the retentive morphology for resin restoration. 2. Dentin surfaces irradiated at below of $42J/cm^2$ with $CO_2$ laser showed the increased acid-resistance. 3. Dentin surfaces irradiated at $218-280J/cm^2$ with Nd:YAG laser showed the retentive morphology. 4. Dentin surfaces irradiated at $218-280J/cm^2$ with Nd:YAG laser and etched 10% maleic acid and then $218-280J/cm^2$ with Nd:YAG laser showed the increased acid-resistance.