• Title/Summary/Keyword: deposition area

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Application of CBD Zinc Sulfide (ZnS) Film to Low Cost Antireflection Coating on Large Area Industrial Silicon Solar Cell

  • U. Gangopadhyay;Kim, Kyung-Hea;S.K. Dhungel;D. Mangalaraj;Park, J.H.;J. Yi
    • Transactions on Electrical and Electronic Materials
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    • v.5 no.1
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    • pp.1-6
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    • 2004
  • Zinc sulfide is a semiconductor with wide band gap and high refractive index and hence promising material to be used as ARC on commercial silicon solar cells. Uniform deposition of zinc sulfide (ZnS) by using chemical bath deposition (CBD) method over a large area of silicon surface is an emerging field of research because ZnS film can be used as a low cost antireflection coating (ARC). The main problem of the CBD bath process is the huge amount of precipitation that occurs during heterogeneous reaction leading to hamper the rate of deposition as well as uniformity and chemical stoichiometry of deposited film. Molar concentration of thiorea plays an important role in varying the percentage of reflectance and refractive index of as-deposited CBD ZnS film. Desirable rate of film deposition (19.6 ${\AA}$ / min), film uniformity (Std. dev. < 1.8), high value of refractive index (2.35), low reflectance (0.655) have been achieved with proper optimization of ZnS bath. Decrease in refractive index of CBD ZnS film due to high temperature treatment in air ambiance has been pointed out in this paper. Solar cells of conversion efficiency 13.8 % have been successfully achieved with a large area (103 mm ${\times}$ 103 mm) mono-crystalline silicon wafers by using CBD ZnS antireflection coating in this modified approach.

Large Area Bernal Stacked Bilayer Graphene Grown by Multi Heating Zone Low Pressure Chemical Vapor Deposition

  • Han, Jaehyun;Yeo, Jong-Souk
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.239.2-239.2
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    • 2015
  • Graphene is a most interesting material due to its unique and outstanding properties. However, semi-metallic properties of graphene along with zero bandgap energy structure limit further application to optoelectronic devices. Recently, many researchers have shown that band gap can be induced in the Bernal stacked bilayer graphene. Several methods have been used for the controlled growth of the Bernal staked bilayer graphene, but it is still challenging to control the growth process. In this paper, we synthesize the large area Bernal stacked bilayer graphene using multi heating zone low pressure chemical vapor deposition (LPCVD). The synthesized bilayer graphenes are characterized by Raman spectroscopy, optical microscope (OM), scanning electron microscopy (SEM). High resolution transmission electron microscopy (HRTEM) is used for the observation of atomic resolution image of the graphene layers.

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Numerical Simulation for Local Circulation of Urban Area and Deposition Phenomenon (도시지역의 국지순환과 침적현상에 관한 수치모의)

  • 이화운;오은주;노순아;반수진
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.6
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    • pp.773-787
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    • 2003
  • There are variations in the temperature Held due to urban heat island and anthropogenic heating so that regional scale meteorological field is changed. Therefore we simulate and predict the regional climate change according to surface characteristics through regional meteorological model. This study investigates the regional meteorological field by urbanization that influences in local circulation system using CSU-RAMS and simulates dry deposition velocity (V$_{d}$) using PNU/DEM which includes surface characteristics (such as albedo, surface hydrology and rough-ness length etc.) with calculated meteorological field. During the summer, horizontal distributions of V$_{d}$ were simulated using CSU-RAMS and PNU/DEM at Busan metropolitan area. The estimated values of V$_{d}$ were larger in forest and agricultural areas than water areas since ozone with low water solubility is destroyed slowly at wet surface or water.water.

Fabrication of 1D Metal Oxide Nanostructures Using Glancing Angle Deposition for High Performance Gas Sensors

  • Suh, Jun Min;Jang, Ho Won
    • Journal of Sensor Science and Technology
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    • v.26 no.4
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    • pp.228-234
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    • 2017
  • Gas sensors based on metal-oxide-semiconductors are predominantly used in numerous applications including monitoring indoor air quality and detecting harmful substances such as volatile organic compounds. Nanostructures, e.g., nanoparticles, nanotubes, nanodomes, or nanofibers, have been widely utilized to improve the gas sensing properties of metal-oxide-semiconductors by increasing the effective surface area participating in the surface reaction with target gas molecules. Recently, 1-dimensional (1D) metal oxide nanostructures fabricated using glancing angle deposition (GAD) method with e-beam evaporation have been widely employed to increase the surface-to-volume ratio significantly with large-area uniformity and reproducibility, leading to promising gas sensing properties. Herein, we provide a brief overview of 1D metal oxide nanostructures fabricated using GAD and their gas sensing properties in terms of fabrication methods, morphologies, and additives. Moreover, the gas sensing mechanisms and perspectives are presented.

Analytic Model for Concentration Deficit Profile Caused by a Large Vegetated Area (녹지의 대기정화효과 분석을 위한 해석적 대기확산모델의 유도)

  • 김석철
    • Journal of Korean Society for Atmospheric Environment
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    • v.16 no.5
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    • pp.539-544
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    • 2000
  • A simple analytic model is proposed here to analyze the concentration deficit field caused by a large area of vegetated area. With non-dimensional deposition velocity chosen as small parameter, the regular perturbation method is exploited to derive the mass balance equation and the dynamic equations for the concentration deficit field, Analytic solutions to those equations are obtained in a closed form for several cases of interest, assuming that the concentration field is stationary and the plume can be nicely approximated as Gaussian for a point source. The results suggest that quite a negligible fraction (less than 1%) of the gaseous air pollutants emitted into the air is removed by the vegetated area of which width is 4 km in wind-wise direction, the typical dimension of the Restricted Development Zones around the metropolitan regions in South Korea.

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Simulation and Characteristic Measurement with Sputtering Conditions of Triode Magnetron Sputter

  • Kim, Hyun-Hoo;Lim, Kee-Joe
    • Transactions on Electrical and Electronic Materials
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    • v.5 no.1
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    • pp.11-14
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    • 2004
  • An rf triode magnetron sputtering system is designed and installed its construction in vacuum chamber. In order to calibrate the rf triode magnetron sputtering for thin films deposition processes, the effects of different glow discharge conditions were investigated in terms of the deposition rate measurements. The basic parameters for calibrating experiment in this sputtering system are rf power input, gas pressure, plasma current, and target-to-substrate distance. Because a knowledge of the deposition rate is necessary to control film thickness and to evaluate optimal conditions which are an important consideration in preparing better thin films, the deposition rates of copper as a testing material under the various sputtering conditions are investigated. Furthermore, a triode sputtering system designed in our team is simulated by the SIMION program. As a result, it is sure that the simulation of electron trajectories in the sputtering system is confined directly above the target surface by the force of E${\times}$B field. Finally, some teats with the above 4 different sputtering conditions demonstrate that the deposition rate of rf triode magnetron sputtering is relatively higher than that of the conventional sputtering system. This means that the higher deposition rate is probably caused by a high ion density in the triode and magnetron system. The erosion area of target surface bombarded by Ar ion is sputtered widely on the whole target except on both magnet sides. Therefore, the designed rf triode magnetron sputtering is a powerful deposition system.

A New Test Method to Evaluate Potential White Pitch Deposit - Influence of pH and calcium hardness - (백색 점착성 이물질을 측정하기 위한 새로운 시험법 - pH와 칼슘경도의 영향 -)

  • Shin, Eun-Ju;Choi, Tae-Ho;Song, Bong-Keun;Cho, Byoung-Uk;Ryu, Jeong-Yong
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.41 no.2
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    • pp.26-33
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    • 2009
  • A new testing method to evaluate the deposition potential of white pitch was developed. The new method involves depositing the potential white pitch particles on the air bubble covered plastic film in the pitch deposit tester (PDT) developed by KRICT and analysing the deposited area of white pitch using an image analyzer. In addition, the effect of two important factors (pH and calcium hardness) on white pitch deposition potential was elucidated. When pH of the coated broke stock was increased from neutral to alkali or the calcium hardness of the stock was decreased, the pitch deposit area was decreased, implying that these two factors have to be controlled during the evaluation of pitch deposition potential. It was found that hydrophobicity of the surface of latex binding films repulped is a key factor influencing white pitch deposition.

Template-directed Atomic Layer Deposition-grown $TiO_2$ Nanotubular Photoanode-based Dye-sensitized Solar Cells

  • Yu, Hyeon-Jun;Panda, Sovan Kumar;Kim, Hyeon-Cheol;Kim, Myeong-Jun;Yang, Yun-Jeong;Lee, Seon-Hui;Sin, Hyeon-Jeong
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.05a
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    • pp.239.1-239.1
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    • 2011
  • Dye sensitized solar cells (DSC) are promising devices for inexpensive, nontoxic, transparent, and large-scale solar energy conversion. Generally thick $TiO_2$ nanoporous films act as efficient photoanodes with their large surface area for absorbing light. However, electron transport through nanoparticle networks causes the slowdown and the loss of electron transport because of a number of interparticle boundaries inside the conduction path. We have studied DSCs with precisely dimension-controlled $TiO_2$ nanotubes array as photoanode. $TiO_2$ nanotubes array is prepared by template-directed fabrication method with atomic layer deposition. Well-ordered nanotubes array provides not only large surface area for light absorbing but also direct pathway for electrons with minimalized grain boundaries. Large enlongated anatase grains in the nanotubes could enhance the conductivity of electrons, but also suppress the recombination with holes through defect sites during diffusion into the electrode. To study the effect of grain boundaries, we fabricated two kinds of nanotubes which have different grain sizes by controlling deposition conditions. And we studied electron conduction through two kinds of nanotubes with different grain structures. The solar cell performance was studied as a function of thickness and grain structures. And overall solar-to-electric energy conversion efficiencies of up to 7% were obtained.

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Synthesis and Characterization of Carbon nanofibers on Co and Cu Catalysts by Chemical Vapor Deposition

  • Park, Eun-Sil;Kim, Jong-Won;Lee, Chang-Seop
    • Bulletin of the Korean Chemical Society
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    • v.35 no.6
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    • pp.1687-1691
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    • 2014
  • This study reports on the synthesis of carbon nanofibers via chemical vapor deposition using Co and Cu as catalysts. In order to investigate the suitability of their catalytic activity for the growth of nanofibers, we prepared catalysts for the synthesis of carbon nanofibers with Cobalt nitrate and Copper nitrate, and found the optimum concentration of each respective catalyst. Then we made them react with Aluminum nitrate and Ammonium Molybdate to form precipitates. The precipitates were dried at a temperature of $110^{\circ}C$ in order to be prepared into catalyst powder. The catalyst was sparsely and thinly spread on a quartz tube boat to grow carbon nanofibers via thermal chemical vapor deposition. The characteristics of the synthesized carbon nanofibers were analyzed through SEM, EDS, XRD, Raman, XPS, and TG/DTA, and the specific surface area was measured via BET. Consequently, the characteristics of the synthesized carbon nanofibers were greatly influenced by the concentration ratio of metal catalysts. In particular, uniform carbon nanofibers of 27 nm in diameter grew when the concentration ratio of Co and Cu was 6:4 at $700^{\circ}C$ of calcination temperature; carbon nanofibers synthesized under such conditions showed the best crystallizability, compared to carbon nanofibers synthesized with metal catalysts under different concentration ratios, and revealed 1.26 high amorphicity as well as $292m^2g^{-1}$ high specific surface area.

Characterization and Construction of Chemical Vapor Deposition by using Plasma (rf 플라즈마 화학기상증착기의 제작 및 특성)

  • 김경례;김용진;현준원;이기호;노승정;최병구
    • Journal of the Korean institute of surface engineering
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    • v.33 no.2
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    • pp.69-76
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    • 2000
  • The rf plasma chemical vapor deposition is a common method employed for diamond or amorphous carbon deposition. Diamond possesses the strongest bonding, as exemplified by a number of unique properties-extraordinary hardness, high thermal conductivity, and a high melting tempera tore. Therefore, it is very important to investigate the synthesis of semiconducting diamond and its use as semiconductor devices. An inductively coupled rf plasma CVD system for producing amorphous carbon films were developed. Uniform temperature and concentration profiles are requisites for the deposition of high quality large-area films. The system consists of rf matching network, deposition chamber, pumping lines for gas system. Gas mixtures with methane, and hydrogen have been used and Si (100) wafers used as a substrate. Amorphous carbon films were deposited with methane concentration of 1.5% at the process pressure of S torr~20 torr, and process temperature of about $750^{\circ}C$. The nucleation and growth of the amorphous carbon films have been characterized by several methods such as SEM and XRD.

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