金属有机化学气相沉积薄膜制备中传热传质的数值模拟

建立水平式GaAs的金属有机化学气相沉积(metal-organic chemical vapor deposition,MOCVD)数学模型, 采用求解压力耦合方程的半隐式(SIMPLE)算法对反应气体流动进行二维数值模拟, 并基于边界层动量、热量与扩散传质的相关理论分析了薄膜制备过程中化学组分的输运, 以及反应前驱物与气相之间的传热过程. 计算所得的GaAs生长速率与实验结果吻合较好. 同时, 数值讨论了反应器进气流量、操作压力以及基底温度对GaAs生长速率的影响. 薄膜生长的速率峰值随入口气体速度的升高而有所增大, 但薄膜生长逐渐趋于不均匀性. 因此, 选取气流速度为0.104 m/s. 薄膜生长速率随着操作压力的增大而增大, 当压力为6 kPa时, GaAs生长速率较压力为2 kPa时提高了223%, 薄膜具有较好的生长速率和均匀性.基底温度对薄膜生长速率影响显著, 在1 050 K时薄膜有良好的生长速率和均匀性, GaAs生长速率比温度为950 K时提高了123%. 研究结果为优化MOCVD反应条件及其反应器的结构设计提供了理论依据.

Numerical simulation of heat and mass transfer processes during preparation of MOCVD film

A mathematical model of metal-organic chemical vapor deposition (MOCVD) process is developed to understand the growth mechanism of GaAs films within a horizontal reactor. Two-dimensional numerical simulation on the reactive gas flow is performed based on the semi-implicit method for pressure-linked equations (SIMPLE). Moreover, the theories of boundary layer on momentum, heat and mass transfer are used to analyze transport of chemical components and heat transfer between the reactor and gas during film preparation. The calculated GaAs growth rate is in agreement with the experimental results, indicating the impacts of intake air flow rate, operating pressure and temperature on the GaAs growth rate. It is revealed that, within the scope of the paper, the film growth rate increases with the rise of inlet gas velocity, while the film gradually exhibits inhomogeneity. Consequently, a flow rate of 0.104 m/s is chosen. By increasing the operating pressure, the film growth rate is increased, evidenced by the GaAs growth rate of 223% at 6 kPa, higher than that for the case of 2 kPa. In other words, it has a higher growth rate and better uniformity. Furthermore, the substrate temperature is a significant effect on the film growth rate as well. The condition of 1 050 K has a high growth rate and good uniformity, with GaAs growth rate being 123% higher than that of 950 K. The present study provides a theoretical understanding for optimizing the reaction conditions and the structure of MOCVD.