• Title/Summary/Keyword: a-Si/c-Si

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A Study on the Properties of SiC Nanotubes: Molecular Dynamics Simulation (탄화규소 나노튜브의 특성에 관한 연구: 분자동역학 전산모사)

  • 문원하;함정국;황호정
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.6
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    • pp.454-459
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    • 2003
  • We investigate the structure and properties of SiC (Silicon Carbide) nanotubes using molecular dynamics simulation based on the Tersoff bond-order potential. For small diameter tubes, the Si-C bond distance of SiC nanotubes decreases as the nanotube diameter is decreased, due to curvature of the nanotube surface. We find that Young's modulus of SiC nanotubes is somewhat smaller than that of the other nanotubes considered so far. However, Young's modulus for SiC nanotubes is larger than that of ${\beta}$-SiC and almost equal to the experimental value for SiC nanorod and SiC whisker. The strain energy of the SiC nanotubes is also lower than that of the other nanotubes. The lower strain energy of SiC nanotubes raises the possibility of synthesis of SiC nanotubes.

Reliability Analysis of 4H-SiC CMOS Device for High Voltage Power IC Integration (고전압 Power IC 집적을 위한 4H-SiC CMOS 신뢰성 연구)

  • Kang, Yeon-Ju;Na, Jae-Yeop;Kim, Kwang-Soo
    • Journal of IKEEE
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    • v.26 no.1
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    • pp.111-118
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    • 2022
  • In this paper, we studied 4H-SiC CMOS that can be integrated with high-voltage SiC power devices. After designing the CMOS on a 4H-SiC substrate, we compared the electrical characteristics with the reliability of high temperature operation by TCAD simulation. In particular, it was confirmed that changing HfO2 as the gate dielectric for reliable operation at high temperatures improves the thermal properties compared to SiO2. By researching SiC CMOS devices, we can integrate high-power SiC power devices with SiC CMOS for excellent performance in terms of efficiency and cost of high-power systems.

Optimization of μc-SiGe:H Layer for a Bottom Cell Application

  • Jo, Jae-Hyeon;Lee, Jun-Sin
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.322.1-322.1
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    • 2014
  • Many research groups have studied tandem or multi-junction cells to overcome this low efficiency and degradation. In multi-junction cells, band-gap engineering of each absorb layer is needed to absorb the light at various wavelengths efficiently. Various absorption layers can be formed using multi-junctions, such as hydrogenated amorphous silicon carbide (a-SiC:H), amorphous silicon germanium (a-SiGe:H) and microcrystalline silicon (${\mu}c$-Si:H), etc. Among them, ${\mu}c$-Si:H is the bottom absorber material because it has a low band-gap and does not exhibit light-induced degradation like amorphous silicon. Nevertheless, ${\mu}c$-Si:H requires a much thicker material (>2 mm) to absorb sufficient light due to its smaller light absorption coefficient, highlighting the need for a high growth rate for productivity. ${\mu}c$-SiGe:H has a much higher absorption coefficient than ${\mu}c$-Si:H at the low energy wavelength, meaning that the thickness of the absorption layer can be decreased to less than half that of ${\mu}c$-Si:H. ${\mu}c$-SiGe:H films were prepared using 40 MHz very high frequency PECVD method at 1 Torr. SiH4 and GeH4 were used as a reactive gas and H2 was used as a dilution gas. In this study, the ${\mu}c$-SiGe:H layer for triple solar cells applications was performed to optimize the film properties.

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Heteroepitaxial Growth of Single 3C-SiC Thin Films on Si (100) Substrates Using a Single-Source Precursor of Hexamethyldisilane by APCVD

  • Chung, Gwiy-Sang;Kim, Kang-San
    • Bulletin of the Korean Chemical Society
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    • v.28 no.4
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    • pp.533-537
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    • 2007
  • This paper describes the heteroepitaxial growth of single-crystalline 3C-SiC (cubic silicon carbide) thin films on Si (100) wafers by atmospheric pressure chemical vapor deposition (APCVD) at 1350 oC for micro/nanoelectromechanical system (M/NEMS) applications, in which hexamethyldisilane (HMDS, Si2(CH3)6) was used as a safe organosilane single-source precursor. The HMDS flow rate was 0.5 sccm and the H2 carrier gas flow rate was 2.5 slm. The HMDS flow rate was important in obtaing a mirror-like crystalline surface. The growth rate of the 3C-SiC film in this work was 4.3 μm/h. A 3C-SiC epitaxial film grown on the Si (100) substrate was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Raman scattering, respectively. These results show that the main chemical components of the grown film were single-crystalline 3C-SiC layers. The 3C-SiC film had a very good crystal quality without twins, defects or dislocations, and a very low residual stress.

Effect of Ti and Si Interlayer Materials on the Joining of SiC Ceramics

  • Jung, Yang-Il;Park, Jung-Hwan;Kim, Hyun-Gil;Park, Dong-Jun;Park, Jeong-Yong;Kim, Weon-Ju
    • Nuclear Engineering and Technology
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    • v.48 no.4
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    • pp.1009-1014
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    • 2016
  • SiC-based ceramic composites are currently being considered for use in fuel cladding tubes in light-water reactors. The joining of SiC ceramics in a hermetic seal is required for the development of ceramic-based fuel cladding tubes. In this study, SiC monoliths were diffusion bonded using a Ti foil interlayer and additional Si powder. In the joining process, a very low uniaxial pressure of ~0.1 MPa was applied, so the process is applicable for joining thin-walled long tubes. The joining strength depended strongly on the type of SiC material. Reaction-bonded SiC (RB-SiC) showed a higher joining strength than sintered SiC because the diffusion reaction of Si was promoted in the former. The joining strength of sintered SiC was increased by the addition of Si at the Ti interlayer to play the role of the free Si in RB-SiC. The maximum joint strength obtained under torsional stress was ~100 MPa. The joint interface consisted of $TiSi_2$, $Ti_3SiC_2$, and SiC phases formed by a diffusion reaction of Ti and Si.

Phase Orientation of TiC-$TiB_2$-SiC Ternary Eutectic Composite Prepared by an FZ Method

  • Tu, Rong;Li, Wenjun;Goto, Takashi
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.859-860
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    • 2006
  • TiC-$TiB_2$-SiC system was a ternary eutectic, whose eutectic composition was 34TiC-$22TiB_2$-44SiC (mol%). TiC-$TiB_2$-SiC ternary eutectic composite were synthesized by a floating zone method using TiC, $TiB_2$ and SiC powders as starting materials. The TiC-$TiB_2$-SiC eutectic composite showed a lamellar texture. TiC(022), $TiB_2(010)$ and SiC(111) of the eutectic composite were perpendicular to the growth direction. TiC-$TiB_2$-SiC ternary eutectic composite had specific relationship among the crystal planes: TiC[011]//$TiB_2[010]$//SiC[112], TiC(200)//$TiB_2$(001)//SiC(402) and $TiC(1\bar{1}1)$//$TiB_2(101)$//SiC(220).

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Effects of In-situ doping Concentration on the Characteristics of Porous 3C-SiC Thin Films (In-situ 도핑량이 다공성 3C-SiC 박막의 특성에 미치는 영향)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.6
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    • pp.487-490
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    • 2010
  • This paper describes the elecrtical and optical characteristics of $N_2$ doped porous 3C-SiC films. Polycrystalline 3C-SiC thin films are anodized by $HF+C_2H_5OH$ solution with UV-LED exposure. The growth of in-situ doped 3C-SiC thin films on p-type Si (100) wafers is carried out by using APCVD (atmospheric pressure chemical vapor deposition) with a single-precursor of HMDS (hexamethyildisilane: $Si_2(CH_3)_6)$. 0 ~ 40 sccm $N_2$ was used for doping. After the growth of doped 3C-SiC, porous 3C-SiC is formed by anodization with $7.1\;mA/cm^2$ current density for anodization time of 60 sec. The average pore diameter is about 30 nm, and etched area is increased with $N_2$ doping rate. These results are attributed to the decrease of crystallinity by $N_2$ doping. Mobility is dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC are 2.5 eV and 2.7 eV, respectively.

Decomposition Behavior of Ferro-Si3N4 for High Temperature Refractory Application (고온 내화물 응용을 위한 질화규소철 (Ferro-Si3N4)의 분해거동)

  • Choi, Do-Mun;Lee, Jin-Seok;Choi, Sung-Churl
    • Journal of the Korean Ceramic Society
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    • v.43 no.9 s.292
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    • pp.582-587
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    • 2006
  • Decomposition behavior of $ferro-Si_3N_4$was investigated with varying temperature and holding time in mud components for high temperature refractory applications. Porosities gradually increased with increasing temperature and holding time due to the carbothermal reduction of $Si_3N_4\;and\;SiO_2$. Silicon monoxide (SiO) as a intermediate resulted from evaporation of $Si_3N_4\;and\;SiO_2$ reacted with C sources to generate needle-like ${\beta}-SiC$ and Fe in $Si_3N_4$ acted as a catalyst in order to enhance growth of SiC grain with the preferred orientation. SiC generation yield increased with increasing holding time, all of the $Si_3N_4\;and\;SiO_2$ affected on SiC formation up to 2h. However, SiC generation was only dependent on residual $SiO_2$ over 2h, because the carbothermal reduction reaction of $Si_3N_4$ was no longer possible at that time.

6.6 kW On-Vehicle Charger with a Hybrid Si IGBTs and SiC SBDs Based Booster Power Module

  • Han, Timothy Junghee;Preston, Jared;Ouwerkerk, David
    • Journal of Power Electronics
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    • v.13 no.4
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    • pp.584-591
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    • 2013
  • In this paper, a hybrid booster power module with Si IGBT and Silicon Carbide (SiC) Schottky Barrier Diode (SBDs) is presented. The switching characteristics of the hybrid booster module are compared with commercial Silicon IGBT/Si PIN diode based modules. We applied the booster power module into a non-isolated on board vehicle charger with a simple buck-booster topology. The performances of the on-vehicle charger are analyzed and measured with different power modules. The test data is measured in the same system, at the same points of operation, using the conventional Si and hybrid Si/SiC power modules. The measured power conversion efficiency of the proposed on-vehicle charger is 96.4 % with the SiC SBD based hybrid booster module. The conversion efficiency gain of 1.4 % is realizable by replacing the Si-based booster module with the Si IGBT/SiC SBD hybrid boost module in the 6.6 kW on-vehicle chargers.

Effect if Grain Size on Plasticity of Ti$_3$SiC$_2$ (Ti$_3$SiC$_2$의 소성 변형 특성에 미치는 결정립 크기의 효과)

  • 이승건
    • Journal of the Korean Ceramic Society
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    • v.35 no.8
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    • pp.807-812
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    • 1998
  • Mechanical properties of two types of polycrystlline {{{{ { { Ti}_{3 }SiC }_{2 } }} with different grain size were investigated. A fine grain {{{{ { { Ti}_{3 }SiC }_{2 } }} has a higher fracture strength and hardness. Plot of strength versus Vickers indentation load indicated that {{{{ { { Ti}_{3 }SiC }_{2 } }} has a high flaw tolerance. Hertzian indentation test using a spherical indenter was used to study elastic and plastic behavior in {{{{ { { Ti}_{3 }SiC }_{2 } }}. Indentation stress-strain curves of each material are made to evaluate the plasticity of {{{{ { { Ti}_{3 }SiC }_{2 } }} Both find and coarse grain {{{{ { { Ti}_{3 }SiC }_{2 } }} showed high plasticity. In-dentation stress-strain curve of coarse grain {{{{ { { Ti}_{3 }SiC }_{2 } }} deviated even more from an ideal elastic limit in-dicating exceptional plasticity in this material. Deformation zones were formed below the contact as well as around the contact area in both materials but the size of deformation zone in coarse grain {{{{ { { Ti}_{3 }SiC }_{2 } }} was much larger than that in fine grain {{{{ { { Ti}_{3 }SiC }_{2 } }} Intragrain slip and kink would account for high plasticity. Plastic behavior of {{{{ { { Ti}_{3 }SiC }_{2 } }} was strongly influenced by grain size.

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