• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.230-230
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• 2013

In amorphous or microcrystalline thin-film silicon solar cells, p-i-n structure is used instead of p/n junction structure as in wafer-based Si solar cells. Hence, these p-i-n structured solar cells inevitably consist of many interfaces and the cell efficiency critically depends on the effective control of these interfaces. In this study, in-situ plasma treatment process of the interfaces was developed to improve the efficiency of a-Si:H solar cell. The p-i-n cell was deposited using a single-chamber VHF-PECVD system, which was driven by a pulsed-RF generator at 80 MHz. In order to solve the cross-contamination problem of p-i layer, high RF power was applied without supplying SiH4 gas after p-layer deposition, which effectively cleaned B contamination inside chamber wall from p-layer deposition. In addition to the p-i interface control, various interface control techniques such as thin layer of TiO2 deposition to prevent H2 plasma reduction of FTO layer, multiple applications of thin i-layer deposition and H2 plasma treatment, H2 plasma treatment of i-layer prior to n-layer deposition, etc. were developed. In order to reduce the reflection at the air-glass interface, anti-reflective SiO2 coating was also adopted. The initial solar cell efficiency over 11% could be achieved for test cell area of 0.2 $cm^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.215-216
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• 2013

The silicide is a compound of Si with an electropositive component. Silicides are commonly used in silicon-based microelectronics to reduce resistivity of gate and local interconnect metallization. The popular silicide candidates, CoSi2 and TiSi2, have some limitations. TiSi2 showed line width dependent sheet resistance and has difficulty in transformation of the C49 phase to the low resistive C54. CoSi2 consumes more Si than TiSi2. Nickel silicide is a promising material to substitute for those silicide materials providing several advantages; low resistivity, lower Si consumption and lower formation temperature. Nickel silicide (NiSi) nanowire (NW) has features of a geometrically tiny size in terms of diameter and significantly long directional length, with an excellent electrical conductivity. According to these advantages, NiSi NWs have been applied to various nanoscale applications, such as interconnects [1,2], field emitters [3], and functional microscopy tips [4]. Beside its tiny geometric feature, NW can provide a large surface area at a fixed volume. This makes the material viable for photovoltaic architecture, allowing it to be used to enhance the light-active region [5]. Additionally, a recent report has suggested that an effective antireflection coating-layer can be made with by NiSi NW arrays [6]. A unique growth mechanism of nickel silicide (NiSi) nanowires (NWs) was thermodynamically investigated. The reaction between Ni and Si primarily determines NiSi phases according to the deposition condition. Optimum growth conditions were found at $375^{\circ}C$ leading long and high-density NiSi NWs. The ignition of NiSi NWs is determined by the grain size due to the nucleation limited silicide reaction. A successive Ni diffusion through a silicide layer was traced from a NW grown sample. Otherwise Ni-rich or Si-rich phase induces a film type growth. This work demonstrates specific existence of NiSi NW growth [7].

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.8
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• pp.129-135
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• 2007

It is necessary to study on the prevention and the management of electrical facilities because the electrical fault took place at the dust occurrence area due to environmental pollution. In particular, the dust accumulates easily on insulation material which is exposed an external long time. Therefore, we measured surface leakage current and surface variation of insulation material due to the dust and salt-water. From the results, the surface of bakelite is bad effect for salt-water than other material. The surface leakage current increases by repeated salt-water pollution and the surface of material is carbonized with arc occurrence. Also, it is need to variation of surface coating and shape of material to repress a leakage current on electrical material.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.65-65
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• 2011

Single-well carbon nanotubes (SWNT) have been proposed as a promising candidate for various applications owing to their excellent properties. In particular, their fascinating electrical and mechanical properties could provide a new area for the development of advanced engineering materials. A transparent conductive thin film (TCF) has increased for applications such as liquid crystal displays, touch panels, and flexible displays. Indium tin oxide (ITO) thin films, which have been traditionally used as the TCFs, have a serious obstacle in TCFs applications. SWNTs are the most appropriate materials for conductive films for displays due to their excellent high mechanical strength and electrical conductivity. But, a bundle of CNTs has different electrical properties than their individual counterparts. In this work, the fabrication by the spraying process of transparent SWNT films and reduction of its sheet resistance on PET substrates is researched. Arc-discharge SWNTs were dispersed in deionized water by adding sodum dodecyl sulfate (SDS) as surfactant and sonicated, followed by the centrifugation. The dispersed SWNT was spray-coated on PET substrate and dried on a hotplate at $100^{\circ}C$. When the spray process was terminated, the TCF was immersed into deionized water to remove the surfactant and then it was dried on hotplate. The TCF film was then treated with ionic doping treatment, rinsed with deionized water and dried. The surface morphology of TCF was characterized by field emission scanning electron microscopy. The sheet resistance and optical transmission properties of the TCF were measured with a four-point probe method and a UV-visible spectrometry, respectively. Results, we show that 97 ${\Omega}$/> sheet resistance can be achieved with 81% transmittance at the wavelength of 550 nm. The changes in electrical and optical conductivity of SWNT film before and after ionic doping treatments were discussed.

• KIEAE Journal
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• v.16 no.3
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• pp.113-119
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• 2016

Purpose: In this study, we evaluate the annual energy performance of the detached house which was designed with the aim of zero energy. Method: The experimental house which was constructed in Gonju Chungnam in 2013, is the single family detached house of light weight wood frame with $100m^2$ of heating area. Thermal transmittance of roof (by ISO 10211) and building external walls are designed as $0.10W/m^2K$ and $0.14W/m^2$ respectively and low-e coating vacuum window glazing with PVC frame was installed. Also grid connected PV system and natural-circulation solar water heater was applied and 6kWp capacity of photovoltaic module was installed in pitched roof and $5m^2$ of solar collector in vertical wall facing the south. We analyzed the 2014 annual data of the detached house in which residents were actually living, measured though web-based remote monitoring system. Result: First, as a result, total annual energy consumption and energy production (PV generation and solar hot water) are 7,919kWh and 7,689kWh respectively and the rate of energy independence is 97.1% which is almost close to the zero energy. Second, plug load and hot water of energy consumption by category showed the highest numbers each with 33% and 31%, with following space heating 24%, electric cooker 8%, lighting 3% in order. Hot water supply is relatively higher than space heating because high insulation makes it decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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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.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.687-693
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• 2004

Composite membranes with a titania layer were prepared by soaking-rolling method with the titania sol of nanoparticles formed in the sol-gel process and investigated regarding the vapor permeation of various organic mixtures. The support modification was conducted by pressing $SiO_2$ xerogel of 500 nm in particle size under 10 MPa on the surface of a porous stainless steel (SUS) substrate and designed the multi-layered structure by coating the intermediate layer of ${\gamma}-Al_2O_3$. Microstructure of titania membrane was affected by heat-treatment and synthesis conditions of precursor sol, and titania formed at calcination temperature of 300$^{\circ}C$ with sol of [$H^+$]/[TIP]=0.3 possessed surface area of 210 $m^2$/g, average pore size of 1.25 nm. The titania composite membrane showed high $H_2/N_2$ selectivity and water/ethanol selectivity as 25-30 and 50-100, respectively. As a result of vapor permeation for water-alcohol and alcohol-alcohol mixture, titania composite membrane showed water-permselective and molecular-sieve permeation behavior. However, water/methanol selectivity of the membrane was very low because of chemical affinity of permeants for the membrane by similar physicochemical properties of water and methanol.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.2
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• pp.88-93
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• 1994

We fabricated a large-scale photovoltaic device for detecting-3-5$\mu$m IR, by forming of n$^{+}$-p junction in the $Hg_{1-x}Cd_{x}$Te (MCT) layer which was grown by LPE on CdTe substrate. The composition x of the MCT epitaxial layer was 0.295 and the hole concentration was 1.3${\times}10^{13}/cm^{4}$. The n$^{+}$-p junction was formed by B+ implantation at 100 keV with a does 3${\times}10^{11}/cm^{2}. The n$^{+}$ region has a circular shape with 2.68mm diameter. The vacuum-evaporated ZnS with resistivity of 2${\times}10^{4}{\Omega}$cm is used as an insulating layer over the epitaxial layer. ZnS plays the role of the anti-reflection coating transmitting more than 90% of 3~5$\mu$m IR. For ohmic contacts, gole was used for p-MCT and indium was used for n$^{+}$-MCT. The fabrication took 5 photolithographic masks and all the processing temperatures of the MCT wafer were below 90$^{\circ}C$. The R,A of the fabricated devices was 7500${\Omega}cm^{2}$. The carrier lifetime of the devices was estimated 2.5ns. The junction was linearly-graded and the concentration slope was measured to be 1.7${\times}10^{17}/{\mu}m$. the normalized detectivity in 3~5$\mu$m IR was 1${\times}10^{11}cmHz^{12}$/W, which is sufficient for real application.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.969-974
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• 2011

A carbon nanotube (CNT) is a cylindrical carbon nanostructure with good transport properties along the tube's axis. As an approach for realizing the practical use of CNTs, CNT networks are fabricated and their applications in many fields are investigated. To fabricate thin CNT-based films, several methods have been proposed and used. Among these methods, the spray coating method is a robust method for fabricating a large area. However, it is difficult to achieve uniformity in the CNT network. To solve this problem, it is necessary to understand the effect of the sprayprocess parameters on the deposition thickness distribution. In this study, a numerical model for predicting the deposition thickness distribution during the spray process was developed. The spatial deposition thickness distributions obtained according to various nozzle paths were analyzed using the developed numerical model.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.399-403
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• 2006

There has been numerous reports for the synthesis of mesoporous $TiO_2$ thin films due to not only the high surface area and regular mesoscale pores but also wide band gap and photo activity. However, the synthesis has been restricted by the limited reproducibility mainly due to the extraordinarily fast hydrolysis and condensation rate of titania precursors. In this report, molar composition of reaction batch (HCl/Ti and Ti/P123) and exterior condition (humidity and temperature) during coating and anealing process. Thereafter, the mesoporous $TiO_2$ thin films were characterized by XRD and TEM