• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.564-570
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• 1996

We have observed the red and blue luminescence from porous silicon (PS) without any rapid thermal oxidation. Aged porous silicon specimens prepared in dilute HF concentration, especially for the short duration of etching, display the increase of the blue band. The measured luminescence decay time at room temperature exhibits a decay time of about 100 ps and shows appreciably faster decay time than that of 20 K. No photoluminescence (PL) peak maximum shift is observed for the blue PL band at 77 K. However, the red PL band shows the blue shift and displays yellow luminescence at 77 K. The origin of red luminescence has some properties related to Si crystallites, whereas blue luminescence seems to be associated other than Si crystallites.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.855-859
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• 2012

Silicon nanowires (SiNWs) were fabricated by a metal-assisted chemical etching of Si and the porous structure on their surfaces was controlled by changing the volume ratio of the etching solution composed of hydrofluoric acid, hydrogen peroxide, and deionized water. The concentration of hydrogen peroxide as the oxidant was varied for controlling the porosity of SiNWs. The optical properties of porous SiNWs were unique and very different from those of single-crystalline Si, as characterized by measuring their photoluminescence and Raman spectra for different porosities.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.90.2-90.2
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• 2010

The crystalline silicon solar cells have been optical losses. but it can be reduced using light trapping by texture structure and anti-reflection coating. The high reflective index of crystalline silicon at solar wavelengths(400nm~1000nm) creates large reflection losses that must be compensated for by applying anti-reflection coating. In this study, the use of porous silicon(PSi) as an active material in a solar cell to take advantage of light trapping and blue-harvesting photoluminescence effect. Porous silicon is form by anodization and can be obtained in an electrolyte with hydrofluoric. We expect our research can results approaching to lower than 10% of several reflectance by porous silicon solar cells.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.68-68
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• 2012

유기 용매를 사용하여 상온에서 실리콘계 전해 도금층을 형성하였다. 도금층의 몰폴로지는 전류밀도 및 도금 시간에 크게 영향을 받았으며, 다공성 구조에서 치밀한 구조까지 다양하게 나타났다. 조성 및 구조가 잘 정의된 실리콘계 전해 도금 층을 리튬이차전지용 애노드 활물질로써 평가해 본 결과 도금층 내 실리콘은 리튬과 가역적으로 반응하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.299-305
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• 1995

Visible photoluminescing (PL) silicon at room temperature has been prepared by a dry technique, that is, by spark processing, contrary to anodically etched porous silicon. PL peak maximum of photoluminescing spark processed Si was shifted to blue 520 nm. The stability of spark processed Si towards degradation upon UV radiation was found to be extremely high. Results from high resolution TEM, XRD and XPS studies suggest that spark processed silicon involves minute nanocrystalline (polycrystalline) particles which are imbedded in an amorphous matrix, preferably $SiO_2$.

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.94-94
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• 1996

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.116.1-116.1
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• 2016

반도체 가스센서에서는 가연성 및 탄화수소계 가스를 감지 하기 위해서 $100{\sim}500^{\circ}C$ 이상의 동작온도를 필요로 한며, 이에 따라 반도체식 가스센서의 마이크로 히터 소재는 고온에서 열적 안정성이 있는 소재가 요구된다. 현재 상용화되고 있는 반도체식 가스센서는 실리콘(Silicon) 기반의 MEMS 기술을 이용한 가스센서이며, 구조적으로나 성능적 한계가 드러남에 따라 실리콘 이외의 다양한 재료의 MEMS 응용기술 개발이 필요한 실정이다. 본 연구에서는 이러한 실리콘의 재료적 한계를 극복하기 위해 다공성 알루미늄 산화물(AAO)을 기판으로 사용하여 마이크로 히터를 제작하였다. AAO의 제작에 앞서 CMP, 화학연마, 전해연마를 이용하여 적합한 전처리 공정을 선정하였고, AAO 제작 시 온도, 시간, 전압의 변수를 주어 마이크로 히터 기판에 적합한 공정을 탐색하였다. 마이크로 플랫폼은 MEMS 공정으로 제작되었으며, PR(Photo Resist)을 LPR(Liquid Photo Resist)과 DFR(Dry Film Resist)로 각각 2종 씩 선택하여 AAO에 적합한 제품을 선정하였다. 제작된 마이크로 히터는 $1.8mm{\times}1,8mm$로 소형화 하였고, 열손실의 제어를 위해 열확산 방지층을 추가하였다. 구동 온도, 소비전력, 장시간 구동시 안정성의 측정 및 평가는 적외선 열화상 카메라와 kiethly 2420 source meter를 이용하여 측정하였으며, 열확산 방지층의 유 무에 따른 온도 분포 및 소비전력을 비교평가 하였다. 최종적으로는 현재 사용화 되어있는 가스센서들의 소비전력과 비교 평가 하여 논의 하였다.

• Journal of the Korean Electrochemical Society
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• v.4 no.1
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• pp.10-13
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• 2001

Effects of an anionic surfactant pentadecafluorooctanoic acid on the photoluminescence of porous silicon was investigated, which was prepared by photoelectrochemical etching at 4V of single crystalline n-type silicon (100) with the specific resistivity of $0.4\~0.8{\Omega}{\cdot}cm$. Photoluminescence shifted to shorter wavelength and its intensity decreased when the concentration of the surfactant increased. FT-IR and contact angle data supported the presence of the surfactant lying on the surface of porous silicon.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.295-298
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• 2007

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.

• Journal of the Korean Ceramic Society
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• v.33 no.5
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• pp.572-582
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• 1996

The porous silicon was prepared in the condition of 70mA/cm2 and 5.10 sec and then oxidized at 800~110$0^{\circ}C$ MOS(Metal Oxide Semiconductor) structure was prepared by Al electrode deposition and analyzed by C-V (Capacitance-Voltage) characteristics. Dielectric constant of oxidized porous silicon was large in the case of low temperature (800, 90$0^{\circ}C$) and short time(20-30min) oxidation and was nearly the same as thermal SiO2 3.9 in the case of high temperature (110$0^{\circ}C$) and long time (above 60 min) It is though to be caused byunoxidized silicon in oxidized porous silicon film and capacitance increase due to surface area increment effect.