• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.31-37
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• 2013

Lowering surface reflectance of Si wafers by texturization is one of the most important processes for improving the efficiency of Si solar cells. This paper presents the results on the effect of texturing using acidic solution mixtures containing the catalytic agents to moderate etching rates on the surface morphology of mc-Si wafer as well as on the performance parameters of solar cell. It was found that the treatment of contaminated crystalline silicon wafer with $HNO_3-H_2O_2-H_2O$ solution before the texturing helps the removal of organic contaminants due to its oxidizing properties and thereby allows the formation of nucleation centers for texturing. This treatment combined with the use of a catalytic agent such as phosphoric acid improved the effects of the texturing effects. This reduced the reflectance of the surface, thereby increased the short circuit current and the conversion efficiency of the solar cell. Employing this technique, we were able to fabricate mc-Si solar cell of 16.4% conversion efficiency with anti-reflective (AR) coating of silicon nitride film using plasma-enhanced chemical vapor deposition (PECVD) and Si wafers can be texturized in a short time.

• Clean Technology
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• v.10 no.1
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• pp.47-51
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• 2004

현재 반도체 공정에서 사용되는 세정기술은 대부분이 1970년대 개발된 RCA 세정법인 과산화수소를 근간으로 하는 습식 세정으로, 표면의 입자를 제거하기 위한 SC-1 세정액은 강력한 산화제인 과산화수소에 의한 표면과 입자의 산화와 암모니아에 의한 표면의 에칭이 동시에 일어나 입자를 표면으로부터 분리시킨다. 금속 불순물을 제거하기 위한 SC-2 세정액은 염산과 과산화수소 혼합액을 사용하며 금속 불순물을 용해시켜 알칼리나 금속 이온을 형성하거나 용해 가능한 화합물을 형성시켜 제거한다. 또한 황산과 과산화수소를 혼합한 Piranha 세정액은 효과적인 유기물 제거제로서 웨이퍼에 오염된 유기물을 용해 가능한 화합물로 만들거나 과산화수소에 의해 형성되는 산화막내에 오염물을 포함시켜 불산 용액으로 산화막을 제거할 때 함께 제거된다. 최근 금속과 산화막을 동시에 제거하기 위해 희석시킨 불산에 과산화수소를 첨가한 세정공정이 사용되고 있으며 불산에 의해 표면의 산화막이 제거될 때 산화막내에 포함된 금속 불순물을 동시에 제거시킬 수 있다. 그러나 이와 같이 습식세정액 내에 공통적으로 포함되어 있는 과산화수소의 분해는 그만큼 가속화되어 사용되는 화학 약품의 양이 그만큼 증가하게 되고 조작하기 어려운 단점도 있다. 이를 해결하기 위해 환경친화적인 관점으로 화학약품의 사용을 최소화하는 등 RCA세정을 보완하는 연구가 계속 진행되고 있다. 본 연구에서는 RCA세정법을 환경적으로 대체할 수 있는 세정에 사용되는 전리수의 pH변화에 따른 전리수 분석을 하였다. 전리수의 제조를 위하여 전해질로는 NH4CI (HCI:H2O:NH4OH=1:1:1)를 사용하였다. pH 11 이상, ORP -700mV~-850mV인 환원수와 pH 3 이하, ORP 1000mV~1200mV인 산화수를 제조하였으며, 초순수를 첨가하여 pH 7.2와 ORP 351.1mV상태까지 조절하였다. 이렇게 만들어진 산화수와 환원수를 시간 변화와 pH 변화에 따라 Clean Room 안에서 FT-IR과 접촉각 측정기로 실험하였다. FT-IR분석에서 산화수는 pH가 높아질수록, 환원수는 낮아질수록 흡수율이 낮아졌다. 접촉각 실험에서는 산화수의 pH가 높아질수록 환원수의 pH가 낮아질수록 접촉각이 커짐을 확인하였다. 결론적으로 전리수를 이용하여 세정을 하면, 접촉성을 조절할 수 있어 반도체 세정을 가능하게 할 수 있으며, 환경친화적인 결과를 도출할 것으로 전망된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.279-282
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• 2001

The IBE(ion beam etching)-induced Schottky barrier variation which depends on various etching history related with ion energy, incident angle and etching time has been investigated using voltage-current, capacitance-voltage characteristics of metal-etched silicon contact and morphology of etched surface were studied using AFM(atomic force microscope). For ion beam etched n-type silicons, Schottky barrier is reduced according to ion beam energy. It can be seen that amount of donor-like positive charge created in the damaged layer is proportional to the ion energy. By contrary, for ion beam etched p-type silicons, the Schottky barrier and specific contact resistance are both increased. Not only etching time but also incident angle of ion beam has an effect on barrier height. Taping-mode AFM analysis shows increased roughness RMS(Root-Mean-Square) and depth distribution due to ion bombardment. Annealing in an N$_2$ ambient for 30 min was found to be effective in improving the diode characteristics of the etched samples and minimum annealing temperatures to recover IBE-induced barrier variation were related to ion beam energy.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.39.1-39.1
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• 2011

본 연구에서는 전해증착법을 이용하여 결정성 ZnTe 나노와이어를 성장시켰고, 구조적 및 전기적 특성을 평가하였다. 또한 나노와이어 성장에 앞서, 결정성 ZnTe 박막을 전해증착법으로 형성하였고, 그 박막의 특성을 관찰하였다. 화학양론적(stoichiometric) 조성을 가지는 박막을 성장시키기 위하여, 순환전류전압법(cyclicvoltammetry)을 이용하여 Zn, Te, 이온들과 구연산 착화체(citrate-complexes)로 구성된 수용액 전해질에서 각 원소의 환원전위 분석이 이루어졌고, 과전압(overpotential)과 전해질 온도와 농도등과 같은 전해증착 조건에 따라 박막을 증착하였다. 각 조건에서 전해증착된 박막은 주사전자현미경(SEM)과 EDS를 이용하여 표면과 두께 그리고 성분분석을 하였고, XRD 분석법을 이용하여 박막의 결정성 변화를 관찰하였다. 박막증착 실험에서의 알맞은 증착조건을 나노와이어 전해증착실험에 적용하여, 다공성의 양극산화알루미늄(Anodic Aluminium Oxide, AAO) 템플레이트를 이용하여 bottom-up 방식으로 결정성 ZnTe 나노와이어를 성장시켰다. 수산화 나트륨(NaOH)용액을 이용하여 템플레이트를 선택적으로 에칭하여 제거한 후, ZnTe 나노와이어의 구조적 및 전기적 특성을 분석하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.977-980
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• 2004

본 논문에서는 저가 고효율 태양전지를 제작하기 위하여 p형 다결정 실리콘 기판을 사용하여 수산화 칼륨(KOH)이 포함된 용액에 Saw damage 과정 후 불산이 함유된 용액에 전기화학적 양극산화 과정으로 실리콘 웨이퍼 표면에 요철을 형성하여 다공성 실리콘을 형성 하였다. 본 논문은 전기화학적 에칭방법으로 기존의 진공장비로 제작된 반사방지막의 반사율만큼 감소된 다공성 실리콘 반사방지막을 형성하였다. 전자빔 증착기(e-beam evaporator)로 단층으로 형성된 $TiO_2$의 반사방지막은 400-1000 nm의 파장 범위에서 4.1 %의 평균 반사율을 가졌으며, 양극산화과정으로 형성된 다공성 실리콘은 400-1000 nm의 파장의 범위에서 4.4 %의 평균 반사율을 가졌다. 본 연구는 태양전지의 반사방지막 형성을 기존의 제작 방법보다 간단하고 저렴한 방법으로 접근하여 태양전지의 변환효율을 상승하는데 목적을 두었다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.12
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• pp.800-805
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• 2017

Randomly patterned and wet chemical etching processes were used to treat anti-glare of display cover glasses. The surface and optical properties of grain size and surface morphology controlled by randomly patterned etching and wet chemical solution etching were investigated. The surface morphology and roughness of the etched samples were examined using a spectrophotometer and a portable surface roughness (Ra) measuring instrument, respectively. The gloss caused by reflection from the glass surface was measured at $60^{\circ}$ using a gloss meter. The surface of the sample etched by the doctor-blade process was more uniform than that obtained from a screen pattern etching process at gel state etching process of the first step. The surface roughness obtained from the randomly patterned etching process depended greatly on the mesh size, which in turn affected the grain size and pattern formation. The surface morphology and gloss obtained by the etching process in the second step depended primarily on the mesh size of the gel state etching process of the first step. In our experimental range, the gloss increased on decreasing the grain size at a lower mesh size for the first step process and for longer reaction times for the second step process.

• Journal of the Korean Geophysical Society
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• v.4 no.2
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• pp.87-93
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• 2001

The roof tiles excavated from the mountain fortress at Namsan-ri Seocheon-gun in Chungnam province were dated by using SAR protocol, Sample preparation was done with the quartz exclusion method. The paleodoses from 6 kinds of roof tiles were obtained from OSL measurements and the does rates of the soil around the excavated roof tiles and the tile themselves were measured from ICP/MS and ICP/AES with the conversion table. From the evaluated paleodose and the dose rate, the age of the roof tiles were determined to be from(733 ± 50)AD to (1160 ± 50)AD and the error was less than 10%.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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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.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.390-393
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• 2009

We report on a new patterning technique for organic functional materials applicable to organic photovoltacis (OPVs). The unconventioal patterning technique, $O_2$ plsama-etching selectively perfluoro-alkyl fluorosilanes, is used for producing a bulk-heterojunction active layer with poly(3-hexylthiophene) as the electron donor and [6,6]-phenyl-$C_{61}$ butyric acid methyl ester as the electron acceptor. The patterning with reduced leakage path and parasitic capacitance suggests a way for fabrication of OPVs with higher energy conversion efficiency.

• Journal of Sensor Science and Technology
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• v.8 no.4
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• pp.308-313
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• 1999

This paper will present an anisotropic etching in TMAH technique used in the fabrication of three-dimensional magnetic field vector sensor based on angled Hall plate structure. This sensor design relies on simultaneously detecting all magnetic field vector components using Hall plates that are imbedded into the silicon [111] sloped-surface of bulk micromachined cavity by the anisotropic etching of [100] silicon. The fabricated Hall elements has relatively improved sensitivity compare to convensional Hall elements for three-dimensional magnetic field sensing. The product sensitivity of 547V/AT at the supply current of 1.0mA was achived. The corresponding limit in the detection of magnrtic field is 0.07G that calculated by measured power spectral density(PSD) in magnetic sensor output.