• 한국전기전자재료학회논문지
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• 제21권2호
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• pp.99-103
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• 2008

To improve efficiency of solar cells, it is important to make a light trapping structure to reduce surface reflectance for increasing absorption of sun light within the solar cells. One of the promising methods that can reduce surface reflectance is isotropic texturing with acid solution based on hydrofluoric acid(HF), nitric acid($HNO_3$), and organic additives. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its different grain orientation. Isotropic texturing with acid solution can uniformly etch multicrystalline silicon wafers unrelated with grain orientation, so we can get low surface reflectance. In this paper, the acid texturing solution is made up of only HF and $HNO_3$ for easy controlling the concentration and low cost compared to acid solution with organic additives. $HNO_3$ concentration and dipping time were varied to find the condition of minimum surface reflectance. Textured surfaces were observed Scanning Electron Microscope(SEM) and surface reflectance were measured. The best result of arithmetic mean(wavelength from 400 nm to 1000 nm) reflectance with acid texturing is 4.64 % less than alkali texturing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.16-17
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• 2007

To improve efficiency of solar cells, it is important to make a light trapping structure to reduce surface reflectance for increasing absorption of sun light within the solar cells. One of the promising methods that can reduce surface reflectance is isotropic texturing with acid solution based on hydrofluoric acid(HF), nitric acid($HNO_3$), and organic additives. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its different grain orientation. Isotropic texturing with acid solution can uniformly etch multicrystalline silicon wafers unrelated with grain orientation, so we can get low surface reflectance. In this paper, the acid texturing solution is made up of only HF and $HNO_3$ for easy controling the concentration and low cost compared to acid solution with organic additives. $HNO_3$ concentration and dipping time were varied to find the condition of minimum surface reflectance. Textured surfaces were observed Scanning Electron Microscope(SEM) and surface reflectance were measured. The best result of arithmetic mean(wavelength from 400nm to 1000nm) reflectance with acid texturing is 4.64% less than alkali texturing.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.264-267
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• 2007

It is important to reduce optical losses from front surface reflection to improve the efficiency of crystalline silicon solar cells. Surface texturing by isotropic etching with acid solution based on HF and $HNO_3$ is one of the promising methods that can reduce surface reflectance. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its various grain orientations. In this paper, we textured multicrystalline silicon wafers by simple wet chemical etching using acid solution to reduce front surface reflectance. After that, surface morphology of textured wafer was observed by Scanning Electron Microscope(SEM) and Atomic Force Microscope(AFM), surface reflectance was measured in wavelength from 400nm to 1000nm. We obtained 29.29% surface reflectance by isotropic texturing with acid solution in wavelength from 400nm to 1000nm for fabrication of multicrystalline silicon solar cells.

• 반도체디스플레이기술학회지
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• 제10권4호
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• pp.31-35
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• 2011

For high efficiency of Si-cells, Si wafers were textured by the KOH and NaOH etching solution to decreas the reflectance at surfaces of the cells. The textured surfaces were shown various types such as isotropic and anisotropic depending on the etching solution. The reflectance at sample of an anisotropic form with pyramid type was lower than that of isotropic form. The surface with isotropic form of general tiny circles on the surface increased the efficiency, however, the reflectance of it was increased. The efficiency was increased on surface with low roughness.

• 한국세라믹학회지
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• 제46권6호
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• 전기화학회지
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• 제14권4호
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• pp.191-195
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• 2011

Wet chemical etching methods were utilized to conduct Si surface texturing, which could enhance photoelectrochemical hydrogen generation rate. Two different etching methods tested, which were anisotropic metal-catalyzed electroless etching and isotropic etching. The Si nano-texture that was fabricated by the anisotropic etching showed ~25% increase in photocurrent for H2 generation. The photocurrent enhancement was attributed to the reduced reflection loss at the nano-textured Si surface, which provided a layer of intermediate density between water and the Si substrate.

• 신재생에너지
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• 제9권2호
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• pp.30-39
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• 2013

Multi-crystalline silicon solar cells is not exist a specific crystal direction different from single crystalline silicon solar cells. In functional materials, therefore, isotropic wet etching of mc-Si solar cell is easy the acid solution rather than the alkaline solution. The reflectance of wet texturing process is about 25% and the reflectance of RIE texturing process is achieved less than 10%. In addition, wet texturing has many disadvantages as well as reflectance. So wet texturing process has been replaced by a RIE texturing process. In order to apply BIPV, RIE and wet textured multi-crystalline silicon solar cell modules was manufactured by different kind of EVA sheet. Moreover, in case of BIPV, the short circuit current characteristics according to the angle of incidence is more important, because the installation of BIPV is fixed location. In this study, we has measured SEM image and I-V curve of RIE and wet textured silicon solar cell and PV module. Also we has analyzed quantum efficiency characteristics of RIE and wet textured silicon solar cell for PV modules depending on incidence angle.

• 한국정보통신학회논문지
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• 제15권11호
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• pp.2439-2443
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• 2011

태양전지를 제작하는데 실리콘기판 표면에서의 광 흡수를 증가시키기 위한 표면조직화를 위해서 염기 용액을 이용한 습식방법을 이용하여 샘플을 제작하였다. 이렇게 준비된 염기성 에칭용액을 이용한 실리콘 웨이퍼의 표면 상태를 관찰하여 광학적 특성과의 연관성을 조사하였다. 표면조직화가 표면 전체적으로 고르게 이루어진 샘플에서 반사도가 낮았으며, 광학적 특성이 좋게 나타났다. 에칭이 과도하게 일어난 샘플에서는 오히려 반사도가 증가하여 광학적 특성이 떨어지는 것을 확인 하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.143-146
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• 2009

One of the most important issues of crystalline silicon solar cell is minimizing reflectance at the surface. Laser texturing is an isotropic process that will sculpt the surface of a silicon wafer, regardless of its crystallographic orientation. We investigated surface texturing process using Nd-YAG laser ($\lambda$=1064 nm) on multi-crystalline silicon wafer. Removal of slag formed after the laser process was performed using acid solution (HF : $HNO_3$ : $CH_3COOH$ : DI water). The reflectance and carrier lifetime of the samples were measured and analyzed using UV-Vis spectrophotometer and carrier lifetime tester. It was found that the minimum reflectance of the samples was 16.39% and maximum carrier life time was $21.8\;{\mu}s$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.280-284
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• 2004

Multicrystalline silicon wafers were textured in an alkaline bath, basically using sodium hydroxide and in acidic bath, using mainly hydrofluoric acid (HF), nitric acid $(HNO_3)$ and de-ionized water (DIW). Some wafers were also acid polished for the comparative study. Comparison of average reflectance of the samples treated with the new recipe of acidic solution showed average diffuse reflectance less than even 5 percent in the optimized condition. Solar cells were thus fabricated with the samples following the main steps such as phosphorus doping for emitter layer formation, silicon nitride deposition for anti-reflection coating by plasma enhanced chemical vapor deposition (PECVD) and front surface passivation, screen printing metallization, co-firing in rapid thermal processing (RTP) Furnace and laser edge isolation and confirmed >14 % conversion efficiency from the best textured samples. This isotropic texturing approach can be instrumental to achieve high efficiency in mass production using relatively low cost silicon wafers as starting material.