• Current Photovoltaic Research
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• v.4 no.1
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• pp.12-15
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• 2016

Screen printing technique followed by firing has commonly been used as metallization for both laboratory and industrial based solar cells. In the solar cell industry, the firing process is usually conducted in a belt furnace and needs to be optimized for fabricating high efficiency solar cells. The printed-Al layer on the silicon is rapidly heated at over $800^{\circ}C$ which forms a layer of back surface field (BSF) between Si-Al interfaces. The BSF layer forms $p-p^+$ structure on the rear side of cells and lower rear surface recombination velocity (SRV). To have low SRV, deep $p^+$ layer and uniform junction formation are required. In this experiment, firing process was carried out by using conventional tube furnace with $N_2$ gas atmosphere to optimize $V_{oc}$ of laboratory cells. To measure the thickness of BSF layer, selective etching was conducted by using a solution composed of hydrogen fluoride, nitric acid and acetic acid. The $V_{oc}$ and pseudo efficiency were measured by Suns-$V_{oc}$ to compare cell properties with varied firing condition.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.335-342
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• 2006

Metal aluminum, of which has a low standard reduction potential, participates in the electrochemical oxidation reaction and results in the structural change and accompanying property variation of aluminum and its oxide film. Aluminum was electrochemically etched in acid solution and the surface area was magnified by the formation of high density etch pits. Etched aluminum was covered with a compact and dense dielectric oxide film by anodization and applied to the capacitor electrode. Anodization of aluminum in acid solution at low temperature makes a nanoporous aluminum oxide layer which can be used for the fabrication template of nanostructural materials. Electrochemical characteristics of aluminum turn the metal aluminum into functional materials and it will bring the diverse applications of metal aluminum.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.53-53
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• 2003

There has been increasing interest in the fabrication of nano-sized structures because of their various advantages and applications. Anodic Aluminum Oxide (AAO) is one of the most successful methods to obtain highly ordered nano pores and channels. Also It can be obtained diverse pore diameter, density and depth through the control of anodization condition. The three types of substrates were used for anodization; sheets of Aluminum on Si wafer and Aluminum on Mo-coated Si wafer. In Aluminum sheet, a highly ordered array of nanoholes was formed by the two step anodization in 0.3M oxalic acid solutions at 10$^{\circ}C$ After the anodization, the remained aluminum was removed in a saturated HgCl$_2$ solution. Subsequently, the barrier layer at the pore bottom was opened by chemical etching in phosphoric acid. Finally, we can obtain the through-channel membrane. In these processes, the effect of various parameters such as anodizing voltage, anodizing time, pore widening time and pre-heat treatment are characterized by FE-SEM (HITACH-4700). The pore size. density and growth rate of membrane are depended on the anodizing voltage and temperature respectively. The pore size is proportional to applied voltage and pore widening time The pore density can be controlled by anodizing temperature and voltage.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.304-307
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• 2007

As to the reflection electrode of LCD (liquid crystal displays), silver-copper-gold alloy (hereafter, it is called as ACA (Ag98%, Cu1%, Au1%)) is an effective material of which weathering resistance can be improved more compared with pure silver. However, there is a problem that gold remains on the substrate as residues when ACA is etched in cerium ammonium nitrate solution or phosphoric acid. Gold can not be etched in these etchants as readily as the other two alloying elements. Gold residue has actually been removed physically by brushing etc. This procedure causes damage to the display elements. Another etchant of iodine/potassium iodide generally known as one of the gold etchants can not give precise etch pattern because of remarkable difference in etching rates among silver, copper and gold. The purpose of this research is to obtain a practical etchant for ACA alloy. The results are as follows. The cyanogen complex salt of gold generates when cyanide is used as the etchant, in which gold dissolves considerably. Oxygen reduction is important as the cathodic reaction in the dissolution of gold. A new etchant of sodium cyanide / potassium ferricyanide whose cathodic reduction is stronger than oxygen, can give precise etch patterns in ACA alloy swiftly at room temperature.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.25-32
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• 2017

In this paper, a fabrication method of low-loss tapered optical fibers coupler using hydrofluoric acid with surface tension driven is proposed. The proposed fabrication method is very simple compared to flame-based method, and shows low excess insertion losses compared to polishing method. The adiabatic-tapered structure along the coupling region of the coupler shows wavelength independent characteristic over the C-band in optical communication system, and will enable promising applications.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2461-2468
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• 2000

In this paper, single fiber pull-out test is used to measure the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory alloy composite with temperature. Fiber and matrix of $Ti_{50}-Ni_{50}$ shape memory alloy composite are respectively $Ti_{50}-Ni_{50}$ shape memory alloy and epoxy resin. To strengthen the interfacial bonding shear stress, various surface treatments are used. They are the hand-sanded surface treatment, the acid etched surface treatment and the silane coupled surface treatment etc.. The interfacial bonding shear strength of surface treated shape memory alloy fiber is greater than that of surface untreated shape memory alloy fiber by from 10% to 16%. It is assured that the hand-sanded surface treatment and the acid etched surface treatment are the best way to strengthen the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory composite. The best treatment condition of surface is 10% HNO$_3$ solution in the etching method to strengthen the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory alloy composite.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.593-597
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• 2003

Anodic aluminum oxide (AAO) membrane was made of aluminum sheet (99.6%, 0.2 mm thickness). The regular array of hexagonal nano pores or channels were prepared by two step anodization process. A detail description of the AAO fabrication is presented. After the 1st anodization in oxalic acid (0.3 M) at 45 V, The formed AAO was removed by etching in a solution of 6 wt% $H_3$$PO_4$＋1.8 wt% $H_2$$CrO_4$. The regular arrangement of the pores was obtained by the 2nd anodization, which was carried out in the same condition as the 1st anodization. Subsequently, the alumina barrier layer at the bottom of the channel layer was removed in phosphoric acid (1M) after removing of aluminum. Pore diameter, density, and thickness could be controlled by the anodization process parameters such as applied voltage, anodizing time, pore widening time, etc. The pore diameter is proportional to the applied voltage and pore widening time. The pore density and thickness can be controlled by anodization temperature and voltage.

• Journal of the korean academy of Pediatric Dentistry
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• v.3 no.1
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• pp.33-39
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• 1976

The present in vitro study was undertaken to evaluate the initial marginal sealing ability of the sealant known as Nuva-Seal to seal cavity margins when used in conjunction with Adaptic and Nuva-Fil restorative materials. The results were as follows; 1. Where each Adaptic and Nuva-Fil restorative material was filled, showed the greatest degree of marginal leakage. 2. Where Adaptic and Nuva-Fil restorative materials were filled after acid etched surrrounding enamel surface adjoining the cavity margins, showed some degree of marginal leakage. 3. Where the Nuva-Seal was applied after acid etching a) to the cavity walls and the peripheral enamel surface adjoining the cavity margins, b) only to the surrounding enamel surface adjoining the cavity margins, and c) over the restorations and the peripheral enamel surface, showed complete absence of marginal leakage of Adaptic and Nuva-Fil restorative materials. 4. Where the Nuva-Seal was applied with the same methods as above, and restorations were placed on thermal stress also showed complete absence of marginal leakage of Adaptic and Nuva-Fil restorative materials.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.926-929
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• 2007

A significant progress has been made in the characterization of zinc oxide (ZnO) semiconductor as a new semiconductor layer instead of amorphous Si semiconductor used in thin film transistor due to its high electron mobility at low deposition temperature which is quite suitable for flexible display and OLED devices. The wet pattering of ZnO is another important issue with regard to mass production of ZnO thin film transistor device. However, the wet behavior of ZnO thin film in aqueous wet etching solutions conventionally used un TFT industry has not been reported yet, in this work, wet corrosion behavior of RF magnetron sputtered ZnO thin film in various wet solutions such as phosphoric and nitric acid solutions was studied using by electrochemical analysis. The effects of deposition parameters such as RF power and oxygen partial pressure on corrosion rate are also examined.

• Journal of the Korean Applied Science and Technology
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• v.14 no.3
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• pp.71-77
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• 1997

Low foaming acidic degreasing agent(LFADAs) were prepared by blending sorbitol, n-octanoic acid, MJU-100A, Tetronix T-701, Na-dioctyl sulfosuccinate, Demol C, and phosphoric acid. The physical properties of LFADAs tested with aluminum specimen showed the following results ; when 3wt% LFADA-6 was performed at $70^{\circ}C$, the degreasing rate was 95% which is comparitively good, and the percentage of etching was 0.275% which was found to be less than that of commercialized product. When 20wt% of LFADA-6 was added at $65^{\circ}C$, the percentage of derusting was 92% and the good defoaming effect proved by following low foaming power tests respectively : Ross and Miles, and Ross and Clark methods.