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MOCVD에 의한 InGaAs, InGaP 및 InGaAsP필름의 성장 및 조성변화에 대한 수치해석 연구
임익태,김동석,김우승,Im, Ik-Tae,Kim, Dong-Suk,Kim, Woo-Seung 한국반도체디스플레이기술학회 2005 반도체디스플레이기술학회지 Vol.4 No.1
Metaloganic chemical vapor deposition, also known as metalorganic vapor phase epitaxy has become one of the main techniques for growing thin, high purity films for compound semiconductors such as GaAs, InP, and InGaAsP. In this study, the distribution of growth rate and composition of InGaAsP, InGaP, and InGaAs films are studied using computational method. The influences of process parameters such as pressure, temperature and precursors' partial pressure on the growth rate and composition distributions are analyzed. The film growth rate is increased in the upstream part according to the increase of temperature but not in the downstream part. The Ga composition in InGaAsP film shows an asymptotic behavior for temperature variation but As composition varies significantly within the temperature range considered in the present study. The overall film growth rates of InGaP, InGaAs and InGaAsP are decreased with increasing the Ga/In ratios of the source gases. Pressure variation does not seem to be a significant parameter to the film growth. Film growth characteristics of tertiary films such as InGaP and InGaAs show similar trends to the quaternary film, InGaAsP.
암시적 VOF법을 이용한 중력주조에서의 충전 및 응고과정에 대한 연구
임익태,김우승,Im, Ik-Tae,Kim, Woo-Seung 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.1
In this study, a three-dimensional gravity casting problem has been examined to investigate a coupled phenomenon of the filling and solidification process. This work simultaneously considers the two key phenomena of metal casting : the fluid flow during mold filling, and solidification process. The VOF method is used to analyze the free surface flow during filling and the equivalent specific heat method is employed to model the latent heat release during solidification. The time-implicit filling algorithm is applied to save the computational time for analyzing the mold filling process. The three-dimensional benchmark problem used in the MCWASP VII has been solved using both the implicit and explicit algorithm, and the present results are compared with the benchmark experimental results and the other numerical results.
임익태,김우승,Im, Ik-Tae,Kim, U-Seung 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.1
The mold filling process has been a central issue in the development of numerical methods to solve the casting processes. A mold filling which is inherently transient free surface fluid flow, is important because the quality of casting highly depends on such phenomenon, Most of the existing numerical schemes to solve mold filling process have severe limitations in time step restrictions or Courant criteria since explicit time integration is used. Therefore, a large computation time is required to analyze casting processes. In this study, the well known SOLA-VOF method has been modified implicitly to simulate the mold filling process. Solutions to example filling problems show that the proposed method is more efficient in computation time than the original SOLA -VOF method.
임익태(Ik-Tae Im),양수현(Su-Hyun Yang),황규남(Kyu-Nam Hwang) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
An annular flume is known as a reasonable laboratory apparatus in the study of characteristics of sediment. It has advantages that it makes the flow be at steady state at anywhere of the flume. However, the bed shear stress distribution across the flume bed is not uniform because of the main stream velocity difference along the radial direction and the secondary flow generated from the centrifugal force. In order to reduce the secondary circulation and the resulting non-uniform radial variation of the bottom shear stress, the body of the flume is counter rotated in the opposite direction of the top-ring. Distribution of bottom shear stress has to be calculated as a function of the rotation ratio between the top-ring and the flume body. In this study, flow field in an annular flume is numerically solved to find the bottom shear stress distribution and a valid range of the bottom shear stress is determined based on the results.
MOCVD 공정을 이용한 GaAs 박막성장의 비선형 표면반응모델에 대한 연구
임익태(Ik-Tae Im) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.3
GaAs film growth process from trimethylgallium(TMGa) and tertiary-butylarsine(TBAs) using a horizontal MOCVD reactor was numerically studied to explain the experimental result that the decreasing surface reaction rate as the increasing partial pressure of group III species. Using the non-linear model based on the Langmuir isotherm which considers the adsorption and desorption of molecules, film deposition over the entire reactor scale was predicted by computational fluid dynamics (CFD) with the aid of the parameters obtained from the selective area growth (SAG) technique. CFD Results using the non-linear surface reaction model with the parameters determined from the SAG experiments predicted too high film growth rate compared to the measured values at the downstream region where the temperature was decreased abruptly. The pairs of (kⁿs , K ) from the numerical simulations was (2.52×10<SUP>-6</SUP> ㏖/㎡/s, 1.6×10?㎥/㏖), whereas the experimentally determined was (3.58×10<SUP>-5</SUP> ㏖/㎡/s, 6.9×10?㎥/㏖).
임익태(Ik-Tae Im),김병호(Byoung Ho Kim),김광선(Kwang-Sun Kim),최낙정(Nag Jung Choi) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Effects of thermal contact resistance between heater and susceptor, susceptor and graphite board in a MOCYD reactor on temperature distribution and film growth rate were analyzed. One-dimensional thermal resistance model considering thermal contact resistance and heat transfer area was made up at first. This one-dimensional model predicted the temperature drop of 18K at the board surface. Temperature distribution from the three-dimensional computational fluid dynamics analysis including the gap at the wafer position showed the temperature drop of 20K. Temperature drop due to the thermal contact resistance affected to the GaAs film growth but not to the InP film growth.
Ⅲ-Ⅴ족 MOCVD 공정의 열전달 및 필름 성장에 대한 연구
임익태(Ik-Tae Im),Yukihiro Shimogaki 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Film growth rate of InP and GaAs using TMI, TMG, TBA and TBP is numerically predicted and compared to the experimental results. Obtained results show that the film growth rate is very sensitive to the thermal condition in the reactor. To obtain exact thermal boundary conditions at the reactor walls, we analyzed the gas flow and heat transfer in the reactor including outer tube as well as the inner reactor parts using a full three-dimensional model. The results indicate that the exact thermal boundary conditions are important to get precise film growth rate prediction.
벽면각도 변화를 통한 환형수조의 바닥전단응력 균일화에 대한 연구
임익태(Ik-Tae Im),양수현(Su-Hyun Yang),황규남(Kyu-Nam Hwang) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
This study proposes a method to suppress secondary flow in a rotating annulus flume and obtain a resulting uniform bottom shear stress distribution along the radial direction by changing the shape of the channel cross section. Two or three wall angles except for the bottom wall angle are simultaneously changed up to 25° for different cross sectional shapes. The flow characteristics in the channel are analyzed using the computational fluid dynamics technique to find the most effective configuration of the walls, including the rotating top-ring. The results show that the bottom shear stress decreases and becomes uniform as the outer wall and the top-ring angles increase. In the case of the inner wall, the wall angle has little effect on the bottom shear stress. The stress distribution is most uniform when the top-ring, the outer wall, and the inner wall angles are 25°, 25°, and 5°, respectively.
수평형 MOCVD 반응기 내의 InP 필름성장 제어인자에 대한 영향 평가
임익태(Ik-Tae Im) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
The InP thin films grown by metalorganic chemical vapor deposition (MOCVD) are widely used to<br/> optoelectronic devices such as laser diodes, wave-guides and optical modulators. Effects of various<br/> parameters controlling film growth rate such as gas-phase reaction rate constant, surface reaction rate constant<br/> and mass diffusivity are numerically investigated. Results show that at the upstream region where film growth<br/> rate increases with the flow direction, diffusion including thermal diffusion plays an important role. At the<br/> downstream region where the growth rate decreases with flow direction, film deposition mechanism is<br/> revealed as a mass-transport limited. Mass transport characteristics are also studied using systematic analyses.