• Title/Summary/Keyword: substrate effects

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The electrical and optical properties of ZnO:Al films Prepared by ultrasonic spray Pyrolysis (초음파 분무법으로 제조한 ZnO:Al 박막의 전기 및 광학적 특성)

  • Lee, Soo-Chul;Moon, Hyun-Yeol;Lee, In-Chan;Ma, Tae-Young
    • Proceedings of the IEEK Conference
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    • 1999.06a
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    • pp.283-286
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    • 1999
  • Transparent conductive aluminum-doped ZnO(AZO) films Were prepared by a ultrasonic spray pyrolysis method at the substrate temperature below 23$0^{\circ}C$. A vertical type hot wall furnace was used as a reactor in the deposition system. Zinc acetate dissolved in methanol was selected as a precursor. The substrate temperature was varied from 18$0^{\circ}C$to 24$0^{\circ}C$. Aluminum (Al) was doped into ZnO films by incorporating anhydrous aluminum chloride (AlCl$_3$) in the zinc acetate solution. The proportion of the Al in the starting solution was varied from 0 wt % to 3.0 wt %. The crystallographic properties and surface morphologies of the films were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The resistivity of the films was measured by the Van der Pauw method, and the mobility and carrier concentration were obtained through the Hall effect measurements Transmittance was measured in the visible region. The effects of substrate temperature and aluminum content in the starling solution on the structural and electrical properties of the AZO films are discussed

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Macro Modeling of MOS Transistors for RF Applications (RF 적용을 위한 MOS 트랜지스터의 매크로 모델링)

  • 최진영
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.5
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    • pp.54-61
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    • 1999
  • We suggested a macro medel for MOS transistors, which incorporates the distributed substrate resistance by using a method which utilizes external diodes on SPICE MOS model. By fitting the simulated s-parameters to the measures ones, we obtained a model set for the W=200TEX>$\mu\textrm{m}$ and L=0.8TEX>$\mu\textrm{m}$ NMOS transistor, and also analyzed the effects of distributed substrate resistance in the RF range. By comparing the physical parameters calculated from simulated s-parameters such as ac resistances and capacitances with the measured ones, we confirmed the validity of the simulation results. For the frequencies below 10GHz, it seems appropriated to use a simple macro model which utilizes the existing SPICE MOS model with junction diodes, after including one lumped resistor each for gate and substrate nodes.

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Surface Characteristics of Polymer Material Treated by Atmospheric Pressure Plasma (상압 플라즈마 표면처리에 의한 고분자 재질의 표면특성변화)

  • Seo, Seung-Ho;Chang, Sung-Hwan;Yoo, Yeong-Eun;Chung, Jae-Dong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.5
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    • pp.282-288
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    • 2010
  • Experiment on the surface characteristics of polymer films treated by atmospheric pressure plasma has been conducted. We chose the process parameters as frequency, gas flow, treatment time, and scrutinized the effects of the process parameters on the surface characteristics of polymer materials by measuring the contact angle and examining SEM. As the result, the surface characteristics highly depends on frequency, reaction gas and treatment time. In the case of PC substrate, the contact angle was changed from $83.5^{\circ}$ (before plasma treatment) to $30^{\circ}$ (after plasma treatment) at 30 kHz, CDA 0.6%, and number of repeat 7. In the case of PET substrate, the contact angle change was found from $59^{\circ}$ to $23.5^{\circ}$ at 20 kHz, CDA 0.6%, and number of repeat 7. In the case of EVA substrate, it shows from $84^{\circ}$ to $44.2^{\circ}$ at 30 kHz, CDA 0.6%, and number of repeat 7.

Wear Mechanism of CrN Coating on Aluminum Alloys Deposited by AIP Method

  • Kim, Seock-Sam;Suh, Chang-Min;Murakami, Ri-ichi
    • KSTLE International Journal
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    • v.3 no.1
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    • pp.43-48
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    • 2002
  • Dry sliding wear and friction test of CrN coaling on two types of aluminum alloy substrates,6061 Al and 7075 Al deposited by arc ion plating, was peformed with a ball-on-disk tribometer. The effects of normal Bead and the mechanical properties of substrate on the friction coefficient and wear-resistance of CrN coating were investigated. The worn surfaces were observed by SEM. The results show that surface micro-hardness of CrN- coated 7075 Al is higher than that of CrN-coated 6061 Al. With an increase in normal lead, wear volume increases, while the friction coefficient decreases. The friction coefficient of CrN-coated 6061 Al is higher than that of CrN-coated 7075 Al, while the wear-resistance of CrN-coated 6061 Al is lower than the CrN-coated 7075 Al's, which indicates that the substrate mechanical properties have strong inf1uences on the friction coefficient and wear of CrN coating. The main wear mechanism was fragments of CrN coating, which were caused by apparent plastic deformation of substrate during wear test.

The Effects of Growth Temperature and Substrate Tilt Angle on GalnP/GaAs Tandem Solar Cells

  • Jun, Dong-Hwan;Kim, Chang-Zoo;Kim, Hog-Young;Shin, Hyun-Beom;Kang, Ho-Kwan;Park, Won-Kyu;Shin, Ki-Soo;Ko, Chul-Gi
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.9 no.2
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    • pp.91-97
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    • 2009
  • The performance of GaInP/GaAs tandem solar cells with AlInP growth temperatures of 680$^{\circ}C$ and 700 $^{\circ}C$ on n-type GaAs (100) substrate with 2$^{\circ}$ and 6$^{\circ}$ tilt angles has been investigated. The series resistance and open circuit voltage of the fabricated tandem solar cells are affected by the substrate tilt angles and the growth temperatures of the window layer when zinc is doped in the tunnel diode. With carbon doping as a p-type doping source in the tunnel diode and the effort of current matching between top and bottom cells, GaInP/GaAs tandem solar cell has been exhibited 25.58% efficiency.

Oxygen Deficiency, Hydrogen Doping, and Stress Effects on Metal-Insulator Transition in Single-Crystalline Vanadium Dioxide Nanobeams

  • Hong, Ung-Gi;Jang, Seong-Jin;Park, Jong-Bae;Bae, Tae-Seong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.424.1-424.1
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    • 2014
  • Vanadium dioxide (VO2) is a strongly correlated oxide exhibiting a first-order metal-insulator transition (MIT) that is accompanied by a structural phase transition from a low temperature monoclinic phase to a high-temperature rutile phase. VO2 has attracted significant attention because of a variety of possible applications based on its ultrafast MIT. Interestingly, the transition nature of VO2 is significantly affected by stress due to doping and/or interaction with a substrate and/or surface tension as well as defects. Accordingly, there have been considerable efforts to understand the influences of such factors on the phase transition and the fundamental mechanisms behind the MIT behavior. Here, we present the influences of oxygen deficiency, hydrogen doping, and substrate-induced stress on MIT phenomena in single-crystalline VO2 nanobeams. Specifically, the work function and the electrical resistance of the VO2 nanobeams change with the compositional variation due to the oxygen-deficiency-related defects. In addition, the VO2 nanobeams during exposure to hydrogen gas exhibit the reduction of transition temperature and the complex phase inhomogenieties arising from both substrate-induced stress and the formation of the hydrogen doping-induced metallic rutile phase.

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A Surface Modification of Hastelloy X by Sic Coating and Ion Beam Mixing for Application in Nuclear Hydrogen Production

  • Kim, Jaeun;Park, Jaewon;Kim, Minhwan;Kim, Yongwan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.205.2-205.2
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    • 2014
  • The effects of ion beam mixing of a SiC film coated on super alloys (hastelloy X substrates) were studied, aiming at developing highly sustainable materials at above $900^{\circ}C$ in decomposed sulfuric acid gas (SO2/SO3/H2O) channels of a process heat exchanger. The bonding between two dissimilar materials is often problematic, particularly in coating metals with a ceramics protective layer. A strong bonding between SiC and hastelloy X was achieved by mixing the atoms at the interface by an ion-beam: The film was not peeled-off at ${\geq}900^{\circ}C$, confirming excellent adhesion, although the thermal expansion coefficient of hastelloy X is about three times higher than that of SiC. Instead, the SiC film was cracked along the grain boundary of the substrate at above $700^{\circ}C$. At ${\geq}900^{\circ}C$, the film was crystallized forming islands on the substrate so that a considerable part of the substrate surface could be exposed to the corrosive environment. To cover the exposed areas and cracks multiple coating/IBM processes have been developed. An immersion corrosion test in 80% sulfuric acid at $300^{\circ}C$ for 100 h showed that the weight retain rate was gradually increased when increasing the processing time.

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Effects of Subatrates Supplemented with Bioceramic. Crushed Shell and Elvanite on the Growth of Watermelon, Cucumber and Tomato Seedlings. (바이오세라믹, 패화석 및 맥반석의 혼입처리가 수박, 오이 및 토마토의 유묘성장에 미치는 영향)

  • 박순기;김홍기;정순주
    • Korean Journal of Organic Agriculture
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    • v.6 no.1
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    • pp.109-116
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    • 1997
  • This experiment was carried out to examine the effect of various functional materials such as bioceramic podwers, crushed shells and elvanites supplemented to the each substrate on the seedlings growth of cucumber, watermelon and tomato. The seedlings were grown in pots filled with substrates of bioceramic podwers, crushed shell and elvanites. The growth of cucumber seedlings in terms of plant height, stem diameter, leaf width, leaf area, plant fresh and dry weight was promoted by adding the bioceramic. powder (1 to 2g/kg), crushed shells (20 to 80g/kg) or elvanites (20 to 80g/kg). Watermelon seedlings in terms of plant height, number of leaves and leaf area were greater than those of the control by adding bioceramics (1 to 2g/kg). Plant height was also promoted by the adding of bioceramic power from 16 days after treatment. But leaf area was increased from 8 days after treatment, while stem diameter was not affected. Watermelon seedlings were also influenced by adding curshed shells (20 to 80g/kg) and elvanites (20 to 40g/kg) into each substrate. The growth of characteristics of tomato seedlings were promoted by adding 1 to 3g/kg of bioceramics, 10 to 80g/kg of crushed shell or 20 to 40g/kg of elvanites, respectively. Especially, root growth was greatly influenced by bioceramic powder, whereas the shoot growth(leaves and stem) was stimulated by crushed shells and elvanites suppemented into substrate.

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Effect of Acvated Oxygen Plasma on the Crystallinity and Superconductivity of $Yba_2Cu_3-O_{7-x}$ Thin Films Prepated by Reactive Co-evaporation method

  • Chang, Ho-Jung;Kim, Byoung-Chul;Akihama, Ryozo;Song, Jin-Tae
    • Korean Journal of Materials Research
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    • v.4 no.3
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    • pp.280-286
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    • 1994
  • As-grown $YBa_2Cu_3O_{7-x}$ films on MgO(100)substrates were prepated by a reactive co-evaporation method, and effects of activated oxygen plasma on the crystallinity and superconductivity at substrate temperature ranging from $450^{\circ}C$ to $590^{\circ}C$ were investigated. The film deposited under the activated oxygen plasma at the substrate temperature of $590^{\circ}C$ had a single crystal phase. Whereas, when films were deposited under only oxygen gas, they were not in perfect single crystal phase but with slight polycrystalline nature. When the substrate temperature was $590^{\circ}C$, $Tc_{zero}$'s were 83K and 80K for films with and without activated oxygen plasma, respectively. The critical temperature, the crystal structure and the surface morphology of as-grown films were found to be insensitive to the activated oxygen plasma which is introduced during deposition instead of oxygen gas, but the crystalline quality was improved somewhat by the introduction by the introduction of actvated oxygen plasma.

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A study on the deposition of DLC thin films by using an FCVA technique (FCVA 방법에 의한 DLC 박막의 제작에 관한 연구)

  • Lee, Hae-Seung;Uhm, Hyun-Seok;Kim, Jong-Kuk;Choi, Byoung-Ryong;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1379-1382
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    • 1997
  • Diamond-like carbon(DLC) thin films are produced by using a filtered cathodic vacuum arc(FCVA) deposition system. Different magnetic components, namely steering, focusing, and filtering plasma-optic systems, are used to achieve a stable arc plasma and to prevent the macroparticles from incorporating into the deposited films. Effects of magnetic fields on plasma behavior and film deposition are examined. The carbon ion energy is found to be varied by applying a negative (accelerating) substrate bias voltage. The deposition rate of DLC films is dependent upon magnetic field as well as substrate bias voltage and at a nominal deposition condition is about $2{\AA}/s$. The structural properties of DLC films, such as internal stress, relative fraction of tetrahedral($sp^3$) bonds, and surface roughness have also been characterized as a function of substrate bias voltages and partial gas($N_2$) pressures.

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