• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.200-206
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• 2000

The metal impurities in specific regions at near surface of silicon wafer were determined by constant depth etching·lt is possible to etch uniformly over the entire wafer surface by 1$\mu\textrm{m}$ depth with 5 mL of etching solution made up of HF and HNO$_3$ mixed by l:3 volume ratio. The microwave oven was used to evaporate the solution after etching. After spiking, The recoveries of Cu, Ni, Zn, Cr, Mg and K were found to be 99∼105%ted in polysilicon region and could be quantified by 1$\mu\textrm{m}$ depth.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1523-1528
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• 2014

Silicon quantum dots (Si QDs) were synthesized by etching silicon nanopowder with aqueous hydrofluoric acid (HF) and nitric acid ($HNO_3$). Then, the hydride-terminated Si QDs (H-Si QDs) were functionalized by 1- octadecene (ODE). By only controlling the etching time, the maximum luminescence peak of octadecylterminated Si QDs (ODE-Si QDs) was tuned from 404 nm to 507 nm. The average optical gap was increased from 2.60 eV (ODE-Si QDs-5 min) for 5 min of etching to 3.20 eV (ODE-Si QDs-15 min) for 15 min of etching, and to 3.40 eV (ODE-Si QDs-30 min) for 30 min of etching. The electron affinities (EA), ionization potentials (IP), and quasi-particle gap (${\varepsilon}^{qp}_{gap}$) of the Si QDs were determined by cyclic voltammetry (CV). The quasi-particle gaps obtained from the CV were in good agreement with the average optical gap values from UV-vis absorption. In the case of the ODE-Si QDs-30 min sample, the difference between the quasi-particle gap and the average optical gap gives the electron-hole Coulombic interaction energy. The additional electronic levels of the ODE-Si QDs-30 min and ODE-Si QDs-15 min samples determined by the CV results are interpreted to have originated from the Si=O bond terminating Si QD.

• Journal of information and communication convergence engineering
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• v.1 no.2
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• pp.67-69
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• 2003

The experimental studies for the etch properties of the oxide grown on silicon substrate, which is in diluted hydrogen fluoride (HF) solution, are presented. Using different ion implantation dosages, dopants and energies, silicon substrate was implanted. The wet etching in diluted HF solution is used as a mean of wafer cleaning at various steps of VLSI processing. It is shown that the wet etch rate of oxide grown on various implanted silicon substrates is a strong function of ion implantation dopants, dosages and energies. This phenomenon has never been reported before. This paper shows that the difference of wet etch rate of oxide by ion implantation conditions is attributed to the kinds and volumes of dopants which was diffused out into $SiO_2$ from implanted silicon during thermal oxidation.

• Korean Journal of Materials Research
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• v.27 no.9
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• pp.501-506
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• 2017

Surface morphology and optical properties such as transmittance and haze effect of glass etched by physical and chemical etching processes were investigated. The physical etching process was carried out by pen type sandblasting process with $15{\sim}20{\mu}m$ dia. of $Al_2O_3$ media; the chemical etching process was conducted using HF-based mixed etchant. Sandblasting was performed in terms of variables such as the distance of 8 cm between the gun nozzle and the glass substrate, the fixed air pressure of 0.5bar, and the constant speed control of the specimen stage. The chemical etching process was conducted with mixed etching solution prepared by combination of BHF (Buffered Hydrofluoric Acid), HCl, and distilled water. The morphology of the glass surface after sandblasting process displayed sharp collision vestiges with nonuniform shapes that could initiate fractures. The haze values of the sandblasted glass were quantitatively acceptable. However, based on visual observation, the desirable Anti-Glare effect was not achieved. On the other hand, irregularly shaped and sharp vestiges transformed into enlarged and smooth micro-spherical craters with the subsequent chemical etching process. The curvature of the spherical crater increased distinctly by 60 minutes and decreased gradually with increasing etching time. Further, the spherical craters with reduced curvature were uniformly distributed over the etched glass surface. The haze value increased sharply up to 55 % and the transmittance decreased by 90 % at 60 minutes of etching time. The ideal haze value range of 3~7 % and transmittance value range of above 90 % were achieved in the period of 240 to 720 minutes of etching time for the selected concentration of the chemical etchant.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.616-621
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• 2009

Reduction of optical losses in crystalline silicon solar cells by surface modification is one of the most important issues of silicon photovoltaics. Porous Si layers on the front surface of textured Si substrates have been investigated with the aim of improving the optical losses of the solar cells, because an anti-reflection coating(ARC) and a surface passivation can be obtained simultaneously in one process. We have demonstrated the feasibility of a very efficient porous Si ARC layer, prepared by a simple, cost effective, electrochemical etching method. Silicon p-type CZ (100) oriented wafers were textured by anisotropic etching in sodium carbonate solution. Then, the porous Si layers were formed by electrochemical etching in HF solutions. After that, the properties of porous Si in terms of morphology, structure and reflectance are summarized. The structure of porous Si layers was investigated with SEM. The formation of a nanoporous Si layer about 100nm thick on the textured silicon wafer result in a reflectance lower than 5% in the wavelength region from 500 to 900nm. Such a surface modification allows improving the Si solar cell characteristics. An efficiency of 13.4% is achieved on a monocrystalline silicon solar cell using the electrochemical technique.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.111-115
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• 2011

Surface Texturing is an essential process for high efficiency in multi-crystalline silicon solar cell. In order to reduce the reflectivity, there are two major methods; proper surface texturing and anti-reflection coating. For texturization, wet chemical etching is a typical method for multi-crystalline silicon. The chemical solution for wet etching consists of HF, $NHO_3$, DI and $CH_3COOH$. We carried out texturization by the change of etching time like 15sec, 30sec, 45sec, 60sec and measured the reflectivity of textured wafers. As making the silicon solar cells, we obtained the conversion efficiency and relationship between texturing condition and solar cell characteristics. The reflectivity from 300nm to 1200nm was the lowest with 15 sec texturing time and 60 sec texturing time showed almost same reflectivity as bare one. The 45 sec texturing time showed the highest conversion efficiency.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.645-650
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• 1997

We manufactured CoNbZr/Cu/CoNbZr multi-layer films by rf magnetron sputtering methods and formed the patterns on the deposited multi-layer films. In this study, we fabricated a new etchant for forming the patterns by the wet etching with etchant and we searched for the best etching conditions and the etchant composition. Cu was etched selectively independent on the concentration of iron chloride solution, but amorphous CoNbZr thin film did not. The etchant was achieved by iron chloride solution(17.5 mol%) mixed with HF (20 mol%) during 150 sec, which etched CoNbZr/Cu/CoNbZr multi-layer films at the same time. Also, the etchant etched CoNbZr/Cu/CoNbZr multi-layer films by the three-step. It was shown that the cross-section had the isotropic structure and excellent etching characteristics with the above etchant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.70-71
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• 2007

Multicrystalline silicon(mc-Si) solar cells are steadily increasing their share of the PV market due to the lower material costs. However, commercial mc-Si solar cells have lower efficiency than singlecrystalline silicon solar cells. To improve efficiency of mc-Si solar cells, it is important to reduce optical losses from front surface reflection. Isotropic etching with acid solution based on hydrofluoric acid(HF) and nitric acid$(HNO_3)$ is one of the promising methods that can reduce surface reflectance for mc-Si solar cells. Anisotropic etching is not suitable for mc-Si because of its various grain orientations. In this paper, we isotropically etched mc-Si using acid solution. After that, etched surface was observed by Scanning Electron Microscope(SEM) and surface reflectance was measured. We obtained 29.29% surface reflectance by isotropic etching with acid solution in wavelength from 400nm to 1000nm for fabrication of mc-Si solar cells.

• Journal of Integrative Natural Science
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• v.5 no.4
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• pp.211-215
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• 2012

Single-crystalline silicon nanowire arrays (SiNWAs) using electroless metal-assisted etchings of p-type silicon were successfully fabricated. Ag nanoparticle deposition on silicon wafers in HF solution acted as a localized micro-electrochemical redox reaction process in which both anodic and cathodic process took place simultaneously at the silicon surface to give SiNWAs. The growth effect of SiNWs was investigated by changing of etching times. The morphologies of SiNWAs were obtained by SEM observation. Well-aligned nanowire arrays perpendicular to the surface of the silicon substrate were produced. Optical characteristics of SiNWs were measured by FT-IR spectroscopy and indicated that the surface of SiNWs are terminated with hydrogen. The thicknesses and lengths of SiNWs are typically 150-250 nm and 2 to 5 microns, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.338.2-338.2
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• 2016

Al doped ZnO (AZO) thin films were deposited on Si substrates with rod-shaped-surface by pulsed laser deposition method (PLD). Si-rods were prepared through chemical etching. To analyze the influence on the formation of the rod structure, samples with various chemical etching conditions such as AgNO3/HF ratio, etching time, and solution temperature were prepared. The morphology of Si-rod structures were examined by FE-SEM. Fig. 1 shows a typical structure of n-AZO/p-Si-rod juncions. The fabricated n-AZO/p-Si-rod devices exhibited p-n diode current-voltage characteristics. We compared the I-V characteristics of n-AZO/p-Si-rod devices with the samples without Si-rod structure.