• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.911-919
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• 1994

As the study for preparation of single-layer anti-reflective coating on glass, the conditions of synthesis of sol for coating and of reproducible coating procedure were investigated. In case of water-based sol, coating was impossible because of poor wettability of sol. The Substitution of solvent with ethanol improved the wettability of sol on the glass surface, and optimum amount of ethanol for substitution was 70 vol%. Maximum specific surface area and total pore volume of water-based sol were 268.7$m^2$/g and 0.315 cc/g, but after substitution, those values increased to 404.1 $m^2$/g and 0.376 cc/g, respectively. The upper limit withdrawl speed of coating in order to get clean coated films without aggregations or stains was 7 cm/min. In case of addition of 0.1 mol HNO3 and substitution with 70 vol% ethanol and heat-treatment at 40$0^{\circ}C$ for 1 hour, thin film with thickness of 94 nm was obtained at withdrawl speed of 4 cm/min. The thickness of thin film was independent of drying time.

• The Journal of the Acoustical Society of Korea
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• v.30 no.1
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• pp.42-48
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• 2011

This preliminary study is about the application of the compound source to the active noise barrier system as control sources. A compound source is composed of two monopole sources but having opposite phase. However, both monopole sources in one compound source are not independently controlled. The source strength of monopole source close to the noise source is proportional to the other one. Therefore, the cost for the hardware system is cheaper than usual system but known to possibly having a similar performance in generating anti-noise acoustic field. In this study, using a simple active noise barrier system model having a non-reflective floor, the effectiveness of the system with compound sources is investigated through computer simulations and shows 30~40 % performance improvement of noise reduction.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.237-242
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• 1998

A transparent and colorless $80SiO_2-20TiO_2$(mol%) thin films on soda-lime-silica slide glass and sapphire substrate were obtained by spin-coating technique using tetraethyl orthosilicate and titanium trichloride as starting materials. The prepared film annealed at $750^{\circ}C$ showed a high transmittance and a low reflectance. For the $SiO_2-TiO_2$ films on slide glasses, a strong interaction between the sodium ion and oxygens is properbly the origin of the good stability to the high temperature and the high humidity.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.7.1-7.1
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• 2011

Nanoporous templates have been widely used for the development of new functional nanostructured materials suitable for electronics, optics, magnetism, and energy storage materials. We have prepared nanoporous templates by using thin films of mixtures of polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) and PMMA homopolymers. These templates have cylindrical nanoholes spanning the entire thickness of the film. Some applications of nanoporous templates are introduced: a) anti-reflective coating, b) the preparation of conducting polymer nanowires of poly (pyrrole), poly (3,4-ethylenedioxy-thiopene) onto a glass coated with indium-tin-oxide, and c) the separation membranes for biomaterials. We found that when the pore fraction of nanoholes in the film was ~0.68, almost zero reflectance at a specific wavelength, which can be changed with film thickness, was achieved at visible wavelengths Furthermore, ultra high density array of conducting nanowires was successfully prepared onto various substrates including flexible polymer. Due to highly alignment of polymer chain along the nanowire direction, the conductivity was much increased. Furthermore, these nanoporous films were found to be very effective for the separation of human Rhinovirus type 14 (HRV 14), major pathogen of a common cold in humans, from the buffer solution. We also found that when the pore size was effectively controlled down to 6 nm, a single file diffusion was observed.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.490-495
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• 1999

In 0.18 $\mu \textrm m$ LOGIC device, the etch rate of NMOS polysilicons is different from that of PMOS polysilicons due to the state of polysilicon to manufacture gate line. To control the etch profile, we tested the ratio of $Cl_2$/HBr gas and the total chamber pressure, and also we reduced Back He pressure to get the vertical profile. In the case of manufacturing the gate photoresist line, we used Bottom Anti-Reflective Coating (BARC) to protect refrection of light. As a result we found that $CF_4O_2$ gas is good to etch BARC, because of high selectivity and good photoresist line profile after etching BARC. in the results of the characterization of plasma damage to the antenna effect of gate oxide, NO type thin film(growing gate oxide in 0, ambient followed by an NO anneal) is better than wet type thin film(growing gate oxide in $0_2+H_2$ ambient).

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1825-1828
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• 2008

A simple method for the fabrication of porous nano-master for antireflective surface is presented. In conventional fabrication methods for antireflective surface, coating method with low refractive index has usually been used. However, it is required to have high cost and long times for mass production. In this paper, we suggested the fabrication method of antireflective surface by the hot embossing process using the porous nano patterned master on silicon wafer fabricated by low-temperature anodic aluminum oxidation. Through multi-AAO and etching processes, nano patterned master with high aspect ratio was fabricated at the large area. Pore diameter and inter-pore distance are about 150nm and from 150 to 200nm. In order to replicate anti-reflective structure, hot embossing process was performed by varying the processing parameters such as temperature, pressure and embossing time etc. Finally, antireflective surface can be successfully obtained after etching process to remove selectively silicon layer of AAO master.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.187-187
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• 2011

Nowadays, the issue of solar cell durability in local weather and environment is a crucial issue. Above all, surface corrosion on solar cell multilayers is a major factor that determines the durability of commercial solar cells; corrosive chemical interactions between air, humidity and chemical species and solar cell multilayers can unfavorably affect the durability. Here, we study microscopic and spectroscopic surface techniques to investigate the corrosive interaction on the antireflective layers of solar cell multilayers under various conditions such as acid, base, constant temperature and humidity. Surface morphology and adhesion force were characterized with atomic force microscopy before and after chemical treatment. Chemical composition, and transmittance factors were studied with X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy, respectively. Based on these studies, we suggest the dominant factors in the corrosive chemical processes, and their influences on the structural, compositional, and optical properties of the antireflective layers.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.218-227
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• 2016

The light harvesting efficiency is counted as an important factor in the power conversion efficiency of DSSCs. There are two measures to improve this parameter, including enhancing the dye-loading capacity and increasing the light trapping in the photoanode structure. In this paper, these tasks are addressed by introducing a macro-porous silicon (PSi) substrate as photoanode. The effects of the novel photoanode structure on the DSSC performance have been investigated by using energy dispersive X-ray spectroscopy, photocurrent-voltage, UV-visible spectroscopy, reflectance spectroscopy, and electrochemical impedance spectroscopy measurements. The results indicated that bigger porosity percentage of the PSi structure improved the both anti-reflective/light-trapping and dye-loading capacity properties. PSi based DSSCs own higher power conversion efficiency due to its remarkable higher photocurrent, open circuit voltage, and fill factor. Percent porosity of 64%, PSi(III), resulted in nearly 50 percent increment in power conversion efficiency compared with conventional DSSC. This paper showed that PSi can be a good candidate for the improvement of light harvesting efficiency in DSSCs. Furthermore, this study can be considered a valuable reference for more investigations in the design of multifunctional devices which will profit from integrated on-chip solar power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.35-40
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• 2012

In this study, the ultraviolet (UV) intensity of polymer insulator was measured using the Anti-Reflective (AR) coating lens on the occurrence of corona discharge. The UV intensity was compared before and after the AR coating. Under the 200-260[nm] of UV lens, the reflection rate before AR coating was 7.5~5.5[%] with 85-89[%] of transmission rate. After AR coating, however, the reflection rate decreased to 1.3~1.22[%] with improved transmission (97.4~97.6[%]). Then, the UV intensity by distance was measured in the polymer insulator. According to the measurement, the UV intensity increased 6.5 times at 37.5[%] of Vm/Vbd with 5[m] of distance. As distance increased, the growth rate declined. As high voltage increased, in addition, AR coating was less effective due to the count error caused by the UV sensor pulse signal overlap. Therefore, it appears that it would be more effective to detect corona discharge with 5[m] or less of distance at diagnosis of power facilities by AR coating and UV sensor sensitivity.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.176-177
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• 2015

최근 자연계에 존재하는 광학 구조체를 모사하여 우수한 반사 방지 효과를 표면에 구현하고자 하는 연구가 이루어지고 있으며, 특히 우수한 무반사 특성을 가지고 있는 나방의 눈 구조를 모사하여 응용하고자 하는 연구가 활발히 진행되고 있다. 하지만, 주로 폴리머를 기판으로 하여 구현되는 모스아이 구조의 필름은 기계적 성질이 좋지 않아 문제가 되고 있다. 따라서, 본 연구에서는 모스아이 나노구조가 형성된 폴리머 기판에 비해 기계적 물성이 우수한 $Al_2O_3$ 물질을 적용하여, 모스아이 패턴의 기계적 특성을 향상 시키면서도, 모스아이 패턴이 가지는 고유의 우수한 광학적 성질을 유지시키기 위한 실험을 진행하였다. 모스아이 패턴의 광학적 성질을 유지하기 위해서는 나노구조 돌기상에 위치에 따른 두께 차이가 최소화된 균일한 코팅층을 형성하여 그 구조를 유지시킬 필요가 있으므로 이러한 구조물상에 단차피복성(Step Coverage)이 우수하고 sub-nm 단위의 정밀한 두께 조절이 용이한 원자층 증착법(Atomic layer deposition, ALD)을 이용하여 박막을 증착하였다.