• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.85-86
• /
• 2006

A theoretical model is applied to the analysis of thermomechanical properties of $Al-SiC_p$ FGMs in this study. Functionally graded $Al-SiC_p$ composites ($Al-SiC_p$ FGMs) consisted with 10 layers gradually changing volume fractions of Al and $SiC_p$ were fabricated using the pressureless infiltration technique. $Al-SiC_p$ FGMs plates of total thickness of 3mm, 5mm and 7mm with fairly uniform distribution and compositional gradient of $SiC_p$ reinforcement in the Al matrix throughout the thickness was successfully fabricated. The curvature of $Al-SiC_p$ FGM plates was measured to check the internal stress distribution predicted via a theoretical model for the analysis of thermo-mechanical deformation. The evolution of curvature and also internal stresses in response to temperature variations could be predicted for the different combinations of geometric thickness of FGM plates. Theoretical prediction of thermally induced stress distribution makes it possible to design FGM structures without any critical failure during the usage of them.

• 태양에너지
• /
• 제20권1호
• /
• pp.11-20
• /
• 2000

To get more insight into the buffering effects of the p-${\mu}c$-Si:H Inserted at the p-a-SiC:H/i-a-Si:H interface, we present a systematic numerical simulation using Gummel-Schafetter method. The reduced recombination loss at the p/i interface due to a constant bandgap buffer is analysed in terms of the variation of the p/i Interface region with a short lifetime and the characterisitics of the buffer such as mobility bandgap, acceptor concentration, and D-state density. The numerical modeling on the constant bandgap buffer demonstrates clearly that the buffering effects of the thin p-${\mu}c$-Si:H originate from the shrinkage of highly defective region with a short lifetime in the vicinity of the p/i interface.

• 한국주조공학회지
• /
• 제15권3호
• /
• pp.262-271
• /
• 1995

It is well known what is impossible to refine primary and eutectic Si simultaneously by addition of both Cu-P and Sr(or Na). Because of the formation of compound $Sr_3P_2(or Na_3P)$ in the melt, in the result, both effects disappear. In this study Al-Cu-P alloy that comprises AlP compounds inside is added in the melt with Sr simultaneously. As AlP compounds that act on nucleation sites of primary Si are not formed but added directly an the melt, it is difficult to form $Sr_3P_2$ by reaction with Sr. Therefore it is possible to refine primary and eutectic Si simultaneously in the general casting process by use of Al-Cu-P alloy and Sr.

• 소성∙가공
• /
• 제13권7호
• /
• pp.608-613
• /
• 2004

Mechanical properties of hypereutectic Al-Si alloy are influenced by the size and distribution of primary Si. To investigate the effects of P addition and holding time, hypereutectic Al-Si alloys with various amount of P content were produced in the lab. Then, the size and distribution of primary Si were examined respectively. Mechanical properties of hardness, tensile strength and wear resistance were analyzed in conjunction with the microstructural variations in alloys.

• 대한전자공학회논문지
• /
• 제27권12호
• /
• pp.1859-1864
• /
• 1990

The effect of H+ and OH- ion concentrations at doped Si semiconductor/pH buffer solution interfaces were investigated in terms of cyclic current-voltage characteristics. The effects of space charge on oppositely doped Si semiconductors, i.e., p-and n-Si semiconductors, can be effectively applied to study the pH effects and the slow surface states at the interfaces. The adsorptions of H+ and OH- inons on the doped Si semiconductor surfaces are physical adsorption rather than chemical adsorption. Adsorptive processes and charging effects of the slow surface states can be explained as the potential barrier variations and the related current-voltage characteristics at the interfaces. Under forward bias, the charged slow surface states on the p-and n-si semiconductor surface are donor and acceptor slow surface states, respectively. The effects of minority carriers on the slow surface states can be neglected at the doped Si semiconductor interfaces.

• 한국재료학회지
• /
• 제7권2호
• /
• pp.145-151
• /
• 1997

AI-xSi/ySiC( x:6~18wt%, y: 3~9wt%, SiC 입자크기: $10~28{\mu}m$) 복합재료를 재용해한 후 항온 유지하고 응고 시킬때 SiC 입자가 몰드의 하부로 침강하는 현상을 계통적으로 조사하였다. AI-Si/SiC 복합재료 용탕을 항온으로 유지하면 입자가 없는 지역은 유지시간이 약 처음 30분 동안 빠르게 증가한다. SiC 입자가 크기가 클수록 SiC입자의 크기가 클수록 SiC입자의 침강속도가 빠르다. 또한 복합재료중 철가한 SiC 입자의 부피분율이 증가하면 입자의 침강속도는 감소한다.

• 한국재료학회지
• /
• 제8권10호
• /
• pp.890-897
• /
• 1998

n-InP(001)기판과 PECVD법으로 ${Si}_3N_4$(200nm)막이 성장된 InP 기판사이의 direct wafer bonding을 분석하였다. 두 기판을 접촉시켰을 때 이들 사이의 결합력에 크게 영향을 주는 표면 상태를 접촉각 측정과 AFM을 통해서 분석하였다. InP 기판은 $50{\%}$ 불산용액으로 에칭하였을 때 접촉각이 $5^{\circ}$, RMS roughness는 $1.54{\AA}$이었다. ${Si}_3N_4$는 암모니아수 용액으로 에칭하였을 때 RMS roughness가 $3.11{\AA}$이었다. Inp 기판과 ${Si}_3N_4$/InP를 각각 $50{\%}$ 불산 용액과 암모니아수 용액에 에칭한 후 접촉시켰을 때 상당한 크기의 초기 겹합력을 관찰할 수 있었다. 기계적으로 결합된 시편을 $580^{\circ}C$-$680^{\circ}C$, 1시간동안 수소 분위기와 질소분우기에서 열처리하였다. SAT(Scanning Acoustic Tomography)측정으로 두 기판 사이의 결합여부를 확인하였다. shear force로 측정한 InP 기판과 ${Si}_3N_4$/InP사이의 결합력은 ${Si}_3N_4$/InP 계면의 결합력만큼 증가되었다. TEM과 AES를 이용해서 di-rect water bonding 계면과 PECVD계면을 분석하였다.

• 한국전기전자재료학회논문지
• /
• 제23권3호
• /
• pp.228-233
• /
• 2010

We studied the optical characteristics correlated with low dielectric constants of low-k SiOCH thin films through ellipsometry. The low-k SiOCH thin films were prepared by CCP-PECVD method using BTMSM(Bis-trimethylsilylmethane) precursors deposited on p-Si wafer. The Si-O-CHx, Si-O-Si, Si-CHx, CHx and Si-H bonding groups were specified by FTIR spectroscopic spectra, and the groups coupled with the nano-porous structural organic/inorganic hybrid-type of SiOCH thin films which has extremely low dielectric constant close to 2.0. The structural groups includes highly dense pore as well as ions in SiOCH thin films affecting to complex refraction characteristics of single layer on the p-Si wafer. The structural complexity originate the complex refractive constants of the films, and resulted the elliptical polarization of the incident linearly polarized light source of Xe-light source in the range from 190 nm to 2100 nm. Phase difference and amplitude ratio between s wave and p wave propagating through SiOCH thin film was studied. After annealing, the amplitude of p wave was reduced more than s wave, and phase difference between p and s wave was also reduced.

• 센서학회지
• /
• 제2권1호
• /
• pp.29-34
• /
• 1993

본 연구에서는 영상센서를 위해 a-Si : H 광다이오드를 제작하고 그 특성을 조사하였다. a-SiN : H와 p-a-Si : H막의 차단층이 없는 ITO/a-Si : H/Al 광다이오드의 광감도는 5 V의 인가전압에서 0.7로 나타났으며 가시광영역에서의 분광감도는 620 nm의 파장에서 가장 높게 나타났다. ITO/a-SiN : H/a-Si : H/p-a-Si : H/Al 광다이오드의 암전류는 정공차단막과 전자차단막의 작용으로 인하여 10V의 인가전압까지 1.5pA이하로 억제되었다. 또한 광감도는 3 V의 인가전압에서 약 1로 가장 높게 나타났으며 분광감도는 540 nm의 파장에서 최대응답을 보였다.

• 소성∙가공
• /
• 제7권2호
• /
• pp.158-167
• /
• 1998

Hot restoration mechanism flow stress and stain of the Al2024 composites reinforced with 1,8,15,36, and $44{\mu}m\;SiC_p$(10 vol. %) were studied by hot torsion tests. The hot restoration mechanism of all the composites was found to be dynamic recrystallization(DRX) at $320^{\circ}C$ while that of the composites reinforced with 1 and $8{\mu}m\;SiC_p$ was found to be dynamic recovery(DRX) at $480^{\circ}C$. It was found that the Al2024 composite with $15{\mu}m\;SiC_p$ showed the highest flow stress(${\sim}$223 MPa) at $320^{\circ}C$ under a strain rate of 1.0/sec. Also the highest flow strain of the composites was obtained at $430^{\circ}C$. The com-posites reinforced with 1 and $8{\mu}m\;SiC_p$ showed lower flow stress and higher flow strain at $480^{\circ}C$ than those of the composites reinforced with 15, 36, and $44\;{\mu}m\;SiC_p$ These result were discussed in relation to the transition of the hot restoration mechanism. $DRX{\leftrightarrow}DRV$. The dependence of flow stress on strain rate and temperature was attempted to fit with the hyperbolic sine equation ($\dot{\varepsilon}=A[sinh({\alpha}{\cdot}{\sigma}_p]^n$ exp(-Q/RT)and Zener-Hollomon parameter($Z=\;\dot{\varepsilon}\;exp(Q/RT))$.