• 제목/요약/키워드: polycrystalline

검색결과 1,290건 처리시간 0.023초

MEMS 부품을 위한 다결정 박막의 탄성 물성치 추출 시스템의 매개변수의 영향 (Parametric Effects of Elastic Property Extraction System of Polycrystalline Thin-Films for Micro-Electro-Mechanical System Devices)

  • 정향남;최재환;정희택;이준기
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.50-54
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    • 2004
  • A numerical system to extract effective elastic properties of polycrystalline thin-films for MEMS devices is already developed. In this system, the statistical model based on lattice system is used for modeling the microstructure evolution simulation and the key kinetics parameters of given micrograph, grain distributions and deposition process can be extracted by inverse method proposed in the system. In this work, the effects of kinetics parameters on the extraction of effective elastic properties of polycrystalline thin-films are studied by using statistical method. The effects of the fraction of the potential site( $f_{P}$ ) and the nucleation probability( $P_{N}$ ) among the parameters for deposition process of microstructure on the extraction of effective elastic properties of polycrystalline thin-films are studied.d.d.

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Interfacial Electrical/Dielectric Characterization in Low Temperature Polycrystalline Si

  • Hwang, Jin-Ha
    • 마이크로전자및패키징학회지
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    • 제12권1호
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    • pp.77-85
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    • 2005
  • Impedance spectroscopy was applied to low temperature polycrystalline Si in order to investigate the electrical/dielectric information in polycrystalline Si. By combined microstructure and impedance spectroscopy works, it was shown that the electrical information is sensitive to the corresponding microstructure, i.e., the grain size and distribution, judged from the capacitance vs. grain size relationship. At $360 mJ/cm^2$, the maximum in capacitance and the minimum in resistance correspond to the largest grain sizes of unimodal distribution in polycrystalline Si. The electrical/dielectric characterization is compared with Raman spectroscopic characterizations in terms of microstructure.

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Cast Poly-Si을 이용한 태양전지 제작 및 특성 (Fabrication and Characterization of Solar Cells Using Cast Polycrystalline Silicon)

  • 구경완;소원욱;문상진;김희영;홍봉식
    • 전자공학회논문지A
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    • 제29A권2호
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    • pp.55-62
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    • 1992
  • Polycrystalline silicon ingots were manufactured using the casting method for polycrystalline silicon solar cells. These ingots were cut into wafers and ten n$^{+}$p type solar cells were made through the following simple process` surface etching, n$^{+}$p junction formation, metalization and annealing. For the grain boundary passivation, the samples were oxidized in O$_2$ for 5 min. at 80$0^{\circ}C$ prior to diffusion in Ar for 100 min. at 95$0^{\circ}C$. The conversion efficiency of polycrystalline silicon solar cells made from these wafers showed about 70-80% of those of the single crystalline silicon solar cell and superior conversion efficiency, compared to those of commercial polycrystalline wafers of Wacker Chemie. The maximum conversion efficiency of our wafers was indicated about 8%(without AR coating) in spite of such a simple fabrication method.

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Structural Control Aiming for High-performance SiC Polycrystalline Fiber

  • Ishikawa, Toshihiro;Oda, Hiroshi
    • 한국세라믹학회지
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    • 제53권6호
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    • pp.615-621
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    • 2016
  • SiC-polycrystalline fiber (Tyranno SA, Ube Industries, Ltd.) shows very high heat-resistance and excellent mechanical properties up to very high temperatures. However, further increase in the strength is required. Up to now, we have already clarified the relationship between the strength and the defect-size of the SiC-polycrystalline fiber. The defects are formed during the conversion process from the raw material (amorphous Si-Al-C-O fiber) into SiC-polycrystalline fiber. In this conversion process, a degradation of the Si-Al-C-O fiber and a subsequent sintering of the degraded fiber proceed as well, accompanied by a release of CO gas and compositional changes, to obtain the dense SiC-polycrystalline fiber. Since these changes proceed in each filament, the strict control should be needed to minimize residual defects on the surface and in the inside of each filament for achieving the higher strength. In this paper, the controlling factors of the fiber strength and the fine structure will appear.

수직 방향 전류를 이용한 폴리실리콘 포토다이오드에 관한 연구 (Investigation of Polycrystalline Silicon Photodiodes Utilizing Vertically Directed Current Path)

  • 송영선;윤일구
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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    • pp.75-76
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    • 2006
  • In this paper, the polycrystalline silicon photodiodes utilizing vertically directed current path are investigated. The location of electrodes is considered with the grain direction and the current path. The relationships between grain boundaries and characteristics of photodiode are simulated to apply the vertically grown polycrystalline silicon to photodiodes. From the results, the vertically grown polycrystalline silicon photodiode is a potential candidate for CMOS image sensor. However, the increment of dark current related to grain boundaries should be reduced.

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다결정 3C-SiC 마이크로 공진기의 온도특성 (Temperature Characteristics of Polycrystalline 3C-SiC Micro Resonators)

  • 정귀상;이태원
    • 한국전기전자재료학회논문지
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    • 제22권4호
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    • pp.314-317
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    • 2009
  • This paper describes the temperature characteristics of polycrystalline 3C-SiC micro resonators. The $1.2{\mu}m$ and $0.4{\mu}m$ thick polycrystalline 3C-SiC cantilever and doubly clamped beam resonators with $60{\sim}100{\mu}m$ lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and their fundamental resonance was measured by a laser vibrometer in vacuum at temperature range of $25{\sim}200^{\circ}C$. The TCF(Temperature Coefficient of Frequency) of 60, 80 and 100 On long cantilever resonators were -9.79, -7.72 and -8.0 ppm/$^{\circ}C$. On the other hand, TCF of 60, 80 and $100{\mu}m$ long doubly clamped beam resonators were -15.74, -12.55 and -8.35 ppm/$^{\circ}C$. Therefore, polycrystalline 3C-SiC resonators are suitable with RF MEMS devices and bio/chemical sensor applications in harsh environments.

Grain Size Effect on Mechanical Properties of Polycrystalline Graphene

  • Park, Youngho;Hyun, Sangil;Chun, Myoungpyo
    • Composites Research
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    • 제29권6호
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    • pp.375-378
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    • 2016
  • Characteristics of nanocrystalline materials are known substantially dependent on the microstructure such as grain size, crystal orientation, and grain boundary. Thus it is desired to have systematic characterization methods on the various nanomaterials with complex geometries, especially in low dimensional nature. One of the interested nanomaterials would be a pure two-dimensional material, graphene, with superior mechanical, thermal, and electrical properties. In this study, mechanical properties of "polycrystalline" graphene were numerically investigated by molecular dynamics simulations. Subdomains with various sizes would be generated in the polycrystalline graphene during the fabrication such as chemical vapor deposition process. The atomic models of polycrystalline graphene were generated using Voronoi tessellation method. Stress strain curves for tensile deformation were obtained for various grain sizes (5~40 nm) and their mechanical properties were determined. It was found that, as the grain size increases, Young's modulus increases showing the reverse Hall-Petch effect. However, the fracture strain decreases in the same region, while the ultimate tensile strength (UTS) rather shows slight increasing behavior. We found that the polycrystalline graphene shows the reverse Hall-Petch effect over the simulated domain of grain size (< 40 nm).

a-plane 사파이어기판에 증착된 Polycrystalline Diamond 박막의 특성 (Characteristics of a Polycrystalline Diamond Thin Film Deposited on a-plane Sapphire Substrate)

  • 싱얀탄;장태환;권진욱;김태규
    • 한국표면공학회지
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    • 제53권3호
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    • pp.109-115
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    • 2020
  • In this study, polycrystalline diamond was synthesized by chemical vapor deposition (CVD). Diamond films were deposited on a-plane sapphire substrates while changing the concentration of methane for hydrogen (CH4/H2), and the concentrations of methane were 0.25, 0.5, 1, 2, 3 and 4 vol%, respectively. Crystallinity and nucleation density according to changes in methane concentration were investigated. At this time, the discharge power, vacuum pressure, and deposition time were kept constant. In order to deposit polycrystalline diamond, the sapphire substrate was etched with sulfuric acid and hydrogen peroxide (ratio 3:7), and the sapphire surface was polished for 30 minutes with 100 nm-sized nanodiamond particles. The deposited diamond thin film was analyzed by a scanning electron microscope (SEM), a Raman spectra, Atomic force microscope (AFM) and an X-ray diffractometer (XRD). By controlling the ratio of methane to hydrogen and performing appropriate pre-treatment conditions, a polycrystalline diamond thin film having excellent crystallinity and nucleation density was obtained.

소성 구배의 영향을 고려한 다결정 고체 내부의 결정 거동 분석 (Evaluation of Effect of Plastic Gradient on the Behavior of Single Grain inside Polycrystalline Solids)

  • 정상엽;한동석
    • 한국방재학회 논문집
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    • 제11권2호
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    • pp.39-44
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    • 2011
  • 마이크로 스케일에서 다결정 재료의 소성 거동을 살펴볼 때, 결정의 geometrically necessary dislocation(GND) 효과에 의한 소성 구배(plastic gradient)를 고려하는 것은 재료의 소성 거동에 큰 영향을 줄 수 있다. 이러한 영향을 확인하기 위하여, 본 연구에서는 소성 구배의 영향을 고려한 다결정 고체(polycrystalline solids)의 거동을 유한요소해석을 이용하여 살펴보았다. 소성 구배의 영향을 살펴보기 위해 구배 경화 계수(gradient hardness coefficient)와 먼 거리 변형률에 대한 재료 길이 변수 (material length parameter)가 사용되었다. 재료 길이 변수에 의한 영향을 확인하기 위해, 재료 길이 변수의 차이에 따른 다결정 고체의 거동을 분석하였다. 또한 소성 구배 효과의 고려 및 재료 길이 변수에 따른 다결정 고체 내부에 위치한 단결정이 받는 영향을 살펴보았다. 재료 길이 변수에 따라 결정이 받는 영향을 비교하여, GND에 의한 다결정 고체 거동의 영향을 확인하였다.

다결정 3C-SiC 마이크로 공진기의 온도 특성 (Fabrication of Pd/poly 3C-SiC Schottky diode hydrogen sensors)

  • 류경일;정귀상
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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    • pp.130-130
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    • 2009
  • This paper describes the temperature characteristics of polycrystalline 3C-SiC micro resonators. The 1.2 ${\mu}m$ and 0.4 ${\mu}m$ thick polycrystalline 3C-SiC cantilever and doubly clamped beam resonators with 60 ~ 100 ${\mu}m$ lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and their fundamental resonance was measured by a laser vibrometer in vacuum at temperature range of $25{\sim}200^{\circ}C$. The TCF(Temperature Coefficient of Frequency) of 60, 80 and 100 ${\mu}m$ long cantilever resonators were -9.79, -7.72 and -8.0 $ppm/^{\circ}C$. On the other hand, TCF of 60, 80 and 100 ${\mu}m$ long doubly clamped beam resonators were -15.74, -12.55 and -8.35 $ppm/^{\circ}C$. Therefore, polycrystalline 3C-SiC resonators are suitable with RF MEMS devices and bio/chemical sensor applications in harsh environments.

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