• Title, Summary, Keyword: SiC

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Thermodynamic Comparison of Silicon Carbide CVD Process between CH3SiCl3-H2 and C3H8-SiCl4-H2 Systems (탄화규소 CVD 공정에서 CH3SiCl3-H2과 C3H8-SiCl4-H2계의 열역학적 비교)

  • Choi, Kyoon;Kim, Jun-Woo
    • Korean Journal of Metals and Materials
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    • v.50 no.8
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    • pp.569-573
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    • 2012
  • In order to understand the difference in SiC deposition between the $CH_3SiCl_3-H_2$ and $C_3H_8-SiCl_4-H_2$ systems, we calculate the phase stability among ${\beta}$-SiC, graphite and silicon. We constructed the phase-diagram of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure (P), temperature (T) and gas composition (C) as variables. Both P-T-C diagrams showed a very steep phase boundary between the SiC+C and SiC region perpendicular to the H/Si axis, and also showed an SiC+Si region with a H/Si value of up to 6700 in the $C_3H_8-SiCl_4-H_2$, and 5000 in the $CH_3SiCl_3-H_2$ system. This difference in phase boundaries is explained by the ratio of Cl to Si, which is 4 for the $C_3H_8-SiCl_4-H_2$ system and 3 for the $C_3H_8-SiCl_4-H_2$ system. Because the C/Si ratio is fixed at 1 in the $CH_3SiCl_3-H_2$ system while it can be variable in the $C_3H_8-SiCl_4-H_2$ system, the functionally graded material is applicable for better mechanical bonding during SiC coating on graphite substrate in the $C_3H_8-SiCl_4-H_2$ system.

Growth of Polycrystalline 3C-SiC Thin Films using HMDS Single Precursor (HMDS 단일 전구체를 이용한 다결정 3C-SiC 박막 성장)

  • Chug, Gwiy-Sang;Kim, Kang-San;Han, Ki-Bong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.2
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    • pp.156-161
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    • 2007
  • This paper describes the characteristics of polycrystalline ${\beta}$ or 3C (cubic)-SiC (silicon carbide) thin films heteroepitaxailly grown on Si wafers with thermal oxide. In this work, the poly 3C-SiC film was deposited by APCVD (atmospheric pressure chemical vapor deposition) method using HMDS (hexamethyildisilane: $Si_{2}(CH_{3}_{6})$ single precursor. The deposition was performed under various conditions to determine the optimized growth conditions. The crystallinity of the 3C-SiC thin film was analyzed by XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction) and FT-IR (fourier transform-infrared spectometers), respectively. The surface morphology was also observed by AFM (atomic force microscopy) and voids or dislocations between SiC and $SiO_{2}$ were measured by SEM (scanning electron microscope). Finally, depth profiling was invesigated by GDS (glow discharge spectrometer) for component ratios analysis of Si and C according to the grown 3C-SiC film thickness. From these results, the grown poly 3C-SiC thin film is very good crystalline quality, surface like mirror and low defect. Therfore, the poly 3C-SiC thin film is suitable for extreme environment, Bio and RF MEMS applications in conjunction with Si micromaching.

Effects of Hot Pressing Condition on the Properties of SiCf/SiC Composites (SiCf/SiC 복합체의 특성에 미치는 열간가압소결 조건의 영향)

  • Noviyanto, Alfian;Yoon, Dang-Hyok
    • Journal of the Korean Ceramic Society
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    • v.48 no.5
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    • pp.335-341
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    • 2011
  • Continuous SiC fiber-reinforced SiC-matrix composites ($SiC_f$/SiC) had been fabricated by electrophoretic infiltration combined with ultrasonication. Nano-sized ${\beta}$-SiC added with 12 wt% of $Al_2O_3-Y_2O_3$ additive and Tyranno$^{TM}$-SA3 fabric were used as a matrix phase and fiber reinforcement, respectively. After hot pressing at 5 different conditions, the density, microstructure and mechanical properties of $SiC_f$/SiC were characterized. Hot pressing at relatively severe conditions, such as $1750^{\circ}C$ for 1 and 2 h, resulted in a brittle fracture behavior due to the strong fiber-matrix interface in spite of their high flexural strength. On the other hand, toughened $SiC_f$/SiC composite could be achieved by hot pressing at milder condition because of the formation of weak interface in spite of the decreased flexural strength. These results proposed the importance of weak fiber-matrix interface in the fabrication of ductile $SiC_f$/SiC composite.

Settling of SiC Particlesin the Al-Si/${SiC}_{p}$ Composite Melts (Al-Si/$\{SiC}_{p}$ 복합재료 용탕에서 SiC 입자의 침강)

  • Kim, Jong-Chan;Gwon, Hyeok-Mu
    • Korean Journal of Materials Research
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    • v.7 no.2
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    • pp.145-151
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    • 1997
  • Remelting of $A-Si/SiC_{p}$ composites followed by isothermal holding and solidification, leads ro the settling of Sic particles to the bottom of the mold. With the isothermal holding time for molten $A-Si/SiC_{p}$ composites. the particle free zone increases rapidly up to approximately first 30 minutes of the holding time. Experimental resulls of the particle settling confirm that the larger SIC particles sink faster tlun the sniiller particles. An increase in volume fraction of Sic particles decreases the setrling velocity of the particles.

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Effect of(Si+C) Content on the Strength of SiC-(Si+C) Sintered Bodies (SiC-(Si+C) 소결체의 강도에 미치는 (Si+C)첨가량의 영향)

  • 김은태;김완덕;최진영;우정인
    • Journal of the Korean Ceramic Society
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    • v.23 no.3
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    • pp.9-14
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    • 1986
  • $\beta$-SiC bonded SiC bodies were prepared from various conditions such as several compositions of(Si+C)/$\alpha$ -SiC ratio and different firing schedules and were respectively investigated compressive strength MOR and mi-crostructure. One firing schedule which produced the specimens that had $\beta$-SiC neck form with the highest strength was selected and experimented by each firing temperature. results obtained are as follows : 1) The amount of (Si+C) for th highest MOR of SiC-(Si+C) sintered body is 20wt% 2) By adding 20wt% content of (Si+C) and heating up to 1, 500 with soaking 3hrs respectively at 1,150$^{\circ}C$ 1,250$^{\circ}C$ 1,350$^{\circ}C$ and 1,400$^{\circ}C$ the highest MOR of fired specimen was resulted and its microstructure of ma-trix was composed of close $\beta$-SiC neck. 3) Microstructure of $\beta$-SiC were different greatly from each other by firing time and/or quantity of adding mix-ture and it was confirmed that they were composed of neck particle-like and heterogeneous texture. 4)$\beta$-SiC synthesis proceed rapidly at the temperature between 1,250$^{\circ}C$ and 1,350$^{\circ}C$ 5) All of the properties of 85 SiC-20(Si+C) specimen improved according to increasing temperature above 1,350$^{\circ}C$.

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Effect of SiC volume fraction on mechanical properties and microstructure of $Si_{3}N_{4}/SiC$ nanocomposites (SiC 부피분율이 $Si_{3}N_{4}/SiC$ 초미립복합재료의 기계적 특성과 미세구조에 미치는 영향)

  • 황광택;김창삼;오근호
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.6 no.3
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    • pp.386-391
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    • 1996
  • SiC particles (average size is 270 nm) of 0, 10, 20, 30, 40 vol% were dispersed in $Si_{3}N_{4}$, and $Si_{3}N_{4}/SiC$ nanocomposites were fabricated by hot press. After sintering, matrix phase, ${\alpha}-Si_{3}N_{4}$ was transformed to ${\beta}-Si_{3}N_{4}$, and second phase, ${\beta}-SiC$ was not changed. No grain boundary crystalline phase by adding of sintering additives was detected. Grain growth of $Si_{3}N_{4}$ was supressed with increasing of SiC contents, and then fine grain was occurred. The highest fracture strength was obtained at 10 vol% SiC, and fracture toughness was decreased, but hardness was linearly increased with SiC content.

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Tribological Behaviour of the Si/SiC and the Si/SiC/Graphite Composites

  • Kim, In-Sub;Shin, Dong-Woo;So, You-Young;Lee, Byung-Ha
    • The Korean Journal of Ceramics
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    • v.3 no.1
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    • pp.47-51
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    • 1997
  • The dense sintered bodies of Si/SiC composite with various Si contents could be fabricated by changing the green density in the forming process. The Si/SiC/graphite composites with various graphite contents could be also fabricated by changing a graphite content in the starting composition. Their mechanical and tribological properties were characterized and wear mechanism was also studided. The hardness and strength of the Si/SiC and the Si/SiC/graphite were decreased with increasing the contents of free Si and graphite, respectively. However, the friction coefficient and specific wear rate had no specific relations to their hardness and strength. Adhesion of free Si was a main factor to determine a wear resistance of the Si/SiC composite. In the case of the Si/SiC/graphite, solid lubricationl and liquid reservoir of the graphite particles played the main role of the reduction of the friction force. In the torque test to estimate the possibility of practical of practical applications, the value of torque between the Al2O3 disk and Si/SiC/graphite disk was 1/6 lower compared with two $Al_2O_3$ disks on the basis of 100,000 cycles.

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Characterization of N-doped SiC(3C) epilayer by CVD on Si(111) (화학기상증착으로 Si(111) 위에 성장된 N-SiC(3C) 에피층의 특성)

  • 박국상;김광철;남기석;나훈균
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.1
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    • pp.39-42
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    • 1999
  • Nitrogen-doped SiC(3C) (N-SiC(3C)) epliayers were grown on Si(111) substrate at $1250^{\circ}C$ using chemical vapor deposition (CVD) technique by pyrolyzing tetramethylsilane(TMS) in $H_{2}$ carrier gas. SiC(3C) layer was doped using $NH_{3}$ during the CVD growth to be n-type conduction. Physical properties of N-SiC(3C) were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) patterns, Raman spectroscopy, cross-sectional transmission electron microscopy (XTEM), Hall measurement, and current-voltage(I-V) characteristcs of the N-SiC(3C)/Si(p) diode. N-SiC(3C) layers exhibited n-type conductivity. The n-type doping of SiC(3C) could be controlled by nitrogen dopant using $NH_{3}$ at low temperature.

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Characteristics of Elastic Wave Generated by Wear and Friction of SiCf/SiC Composites (SiCf/SiC 복합재의 마모 및 마찰에 의해 발생된 탄성파 특성)

  • Moon, Chang-Kwon;Nam, Ki-Woo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.1
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    • pp.23-30
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    • 2014
  • The wear characteristics of $SiC_f$/SiC composites were evaluated according to the alignment direction of the fibers, and the elastic wave-generated friction was detected and analyzed in wearing. The friction coefficient and wear loss were similar in the longitudinal and the transverse direction of the fibers. However, these values were lower in the vertical direction of the fibers because of the brittle nature of the fiber. The friction coefficient and the wear loss were directly proportional to each other. The dominant frequencies were 58.6 kHz for monolithic SiC and 117.2 and 136.7 kHz for $SiC_f$/SiC composites, respectively.

Roles of i-SiC Buffer Layer in Amorphous p-SiC/i-SiC/i-Si/n-Si Thin Film Solar Cells (비정질 p-SiC/i-SiC/i-Si/n-Si 박막 태양전지에서 i-SiC 완충층의 역할)

  • Kim, Hyun-Chul;Shin, Hyuck-Jae;Lee, Jae-Shin
    • Korean Journal of Materials Research
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    • v.9 no.12
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    • pp.1155-1159
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    • 1999
  • Thin film solar cells on a glass/$SnO_2$ substrate with p-SiC/i-Si/n-Si heterojunction structures were fabricated using a plasma-enhanced chemical-vapor deposition system. The photovoltaic properties of the solar cells were examined with varying the gas phase composition, x=$CH_4/\;(SiH_4+CH_4)$, during the deposition of the p-SiC layer. In the range of x=0~0.4, the efficiency of solar cell increased because of the increased band gap of the p-SiC window layer. Further increase in the gas phase composition, however, led to a decrease in the cell efficiency probably due to in the increased composition mismatch at the p-SiC/i-Si layers. As a result, the efficiency of a glass/$SnO_2$/p-SiC/i-SiC/i-Si/n-Si/Ag thin film solar cell with $1cm^2$ area was 8.6% ($V_{oc}$=0.85V, $J_{sc}$=16.42mA/$cm^2$, FF=0.615) under 100mW/$cm^2$ light intensity.

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