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InP에서의 Zn₃P₂ 박막 및 RTA법에 의한 Zn 확산의 특성
우용득(Yong-Deuk Woo) 한국진공학회(ASCT) 2004 Applied Science and Convergence Technology Vol.13 No.3
InP에서 열처리 온도와 시간 및 활성화 온도에 따른 Zn의 확산의 특성을 electrochemical capacitance-voltage 법으로 조사하였다. InP층은 metal organic chemical vapor deposition를 이용하여 성장하였으며, 확산방법으로는 Zn₃P₂ 확산원 박막과 rapid thermal annealing를 사용하였다. 최대의 정공 농도를 갖는 p-InP 층은 550 ℃에서 5분 동안 확산과 활성화를 한 시료에서 얻었고, Zn의 농도는 1×10^(19) ㎝-³이었다. 550 ℃에서 5+20 분 동안 확산을 수행한 결과 정공농도의 확산 깊이는 1.51㎛에서 3.23㎛로 이동하였고, Zn의 확산계수는 5.4×10^(-11) ㎠/sec이었다. 활성화 시간의 증가로, Zn가 더 깊게 확산하지만, 정공농도는 거의 변화가 없었다. 이는 도핑된 영역의 과잉의 침입형 Zn가 도핑되지 않은 영역으로 빠르게 확산하고 치환형 Zn로 변한다는 것을 의미한다. 정공농도는 SiO₂ 박막의 두께가 1,000Å 이상이어야 안정적으로 분포된다. Zn diffusions in InP have been studied by electrochemical capacitance voltage. The InP layer was grown by metal organic chemical vapor deposition, and Zn₃P₂ thin film was deposited on the epitaxial substrates. The samples annealed in a rapid thermal annealing. It is demonstrated that surface hole concentration as high as 1×10^(19) cm-³ can be achieved. When the Zn diffusion was carried at 550℃ and 5-20 min., the diffusion depth of hole concentration moves from 1.51 ㎛ to 3.23 ㎛, and the diffusion coefficient of Zn is 5.4×10^(-11) ㎠/sec. After activation, the concentration is two orders higher than that of untreated sample at 0.30 ㎠ depth. As the annealing time is increase, the hole concentration remains almost constant, except deep depth. It means that excess Zn interstitials exist in the doped region is rapidly diffusion into the undoped region and convert into substitutional when the thickness of SiO₂ thin film is above 1,000Å, the hole concentration becoms stable distribution.
비접촉 EMAT를 이용한 CFRP 복합재료의 적층결함 비파괴평가에 관한 연구
임광희(Kwang-Hee Im),우용득(Yong-Deuk Woo),조성호(Sung-Ho Cho),유휘룡(Hui-Ryong Yoo),노용우(Yong-Woo Rho),김학준(Hak-Joon Kim),David K. Hsu 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
An electromagnetic acoustic transducers (EMAT) can usually generate or detect an ultrasonic wave into specimens across a small gap. Especially stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates because the layup of composite laminates influences there properties. It is very important to evaluate the layup errors in prepreg laminates. A nondestructive technique can therefore serve as a useful measurement for detecting layup errors. It was shown experimentally that this shear waves for detecting the presence of the errors is very sensitive. It is found that high probability shows between tests and the model developed in characterizing cured layups of the laminates. Also a C-scan method was used for detecting layup of the laminates because of extracting fiber orientation information from the ultrasonic reflection caused by structural imperfections in the laminates. Therefore, it was found that interface C-scan images show the fiber orientation information by using two-dimensional fast Fourier transform(2-D FFT).
임광희(Kwang-Hee Im),우용득(Yong-Deuk Woo),이호석(Ho-Seuk Lee),임재실(Je-Sil Lim) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4
It is well known that food garbages cause serious problem to our environments. The best way to decrease the food garbage is that we will reduce the food waste at the point cooking and eating. However, there are some limitations to reduce. So, an automatic system of food garbage disposal was manufactured, which brought the waste food to cut down the weight and then to treat the food on the trash can with sanitation. Also, this machine will make the environment to be pleasant and nice place
임광희(Kwang-Hee Im),이슬기(Seul-Ki Lee),김학준(Hak-Joon Kim),송성진(Sing-Jin Song),우용득(Yong-Deuk Woo),나승우(Sung-Woo Na),황우채(Woo-Chae Hwang),이형호(Hyung-Ho Lee) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.6
A defect could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size, applied frequency were calculated based on the simulation results. Simulations were carried out for the defect signal of eddy current probe. Exciter and receiver were utilized. In this paper, the FEM simulations were performed in both bobbin-type and pancake-type probe, both probes were optimized under Eddy current FEM simulations and the results of calculation were discussed.
Pseudomorphic In_xGa_(1-x)As(0.53<x<0.70)/In_0.53Al_0.47As HEMT의 전자이동도
우용득,이해익 又石大學校 1994 論文集 Vol.16 No.-
Temperature dependent Hall effect measurements were performed on the modulation doped n-type pseudomorphic In_xGa_1-xAs(x=0.53, 0.60, 0.65, and 0.70)/In_0.53Al_0 .47As HEMT grown by molecular beam epitaxy. The temperature was varied from 10K to 300K, For the sample with x=0.70, the measured value of electron mobility are 17,939,63,066, and 71,785㎠/V.s at 300, 77, and 10K respectively. Electron mobility and carrier concentration are enhanced as the In mole fraction in the channel increases. We have confirmed that the improvement is due to the reduction of alloy scattering, ionized remote impurity scattering, and intersubband scattering etc., all of which result from a large conduction band offset and increased carrier confinement in the two dimensional electron gas.
Ge 완충층의 사용과 Ge 완충층의 in situ 열처리 온도의 변화에 대한 GaAs/Ge/Si 계면에서 전위의 거동
우용득,이해익 又石大學校 1998 論文集 Vol.20 No.-
Effect of in-situ annealing after the Ge buffer layer growth on the behavior of defects at the interfaces of GaAs/Ge/Si structure grown by molecular beam epitaxy(MBE) were investigated using transmission electron microscopy (TEM) technique. Results show that the threading dislocations toward the GaAs layers were blocked more efficiently at the Ge/GaAs interface, when an in situ thermal annealing at 750℃ for 10 minutes was performed after the Ge buffer layers Growth. It was also observed that dislocation density was independent on the thickness of Ge buffer layer. Neither stacking faults nor microtwins were observed in the samples studied. probably because surface morphology of the Ge buffer layer improved due to the in situ annealing and nucleation of the defects was suppressed a result.
MBE로 성장한 Sn/GaAs(100)층의 초기성장과 Annealing효과
우용득 동국대학교 대학원 1991 大學院硏究論集-東國大學校 大學院 Vol.21 No.-
The initial growth mode of Sn overlayers on GaAs(100) surface and the surface variation due to annealing were investigated by Auger electron spectroscopy (AES), reflection high energy electron diffraction(RHEED) and scanning electron microscopy (SEM), At room temperature, Sn was grown up to 3ML with layer by layer growth mode and with Stranski-Krastanov growth mode at higher MLs. After growing up to 10ML, crystal properties are recovered by annealing at 700K. 10ML Sn/ GaAs and GaAs/Sn/GaAs have lattice constants between GaAs and β-Sn by annealing. GaAs was grown on the Sn overlayers with thickness of 10ML and good surface morphology was achieved.
Si 기판위에 분자선 에피탁시법으로 성장된 Si_1-xGe_x 에피층의 특성
우용득,이해익 又石大學校 1996 論文集 Vol.18 No.-
The Si_(1-x)Ge_x epilayers grown on Si substrate by molecular beam epitaxy(MBE) have been studied as a function of growth temperature and Ge mole fraction by using transmission electron microscopy. double crystal x-ray diffraction, and Raman spectroscopy. TEM for these samples reveals that there are a lot of dislocations at the Si_(1-x)Ge_x/Si interface. The strain of epilayer in Si_(1-x)Ge_x was increased as the composition of Ge increases. To relaxe the strain, increment of threading dislocation was confirmed by Raman and TEM results. In the Si_(0.6)Ge_(0.4)/Si, the physical properties may be obtained when the growth temperature is held at 500℃