Abstract In the modeling of the reaction-transport process in GaN MOVPE growth, the selections of kinetic parameters (activation energy Ea and pre-exponential factor A) for gas reactions are quite uncertain, which cause uncertainties in both gas reaction path and growth rate. In this study, numerical modeling of the reaction-transport process for GaN MOVPE growth in a vertical rotating disk reactor is conducted with varying kinetic parameters for main reaction paths. By comparisons of the molar concentrations of major Ga-containing species and the growth rates, the effects of kinetic parameters on gas reaction paths are determined. The results show that, depending on the values of the kinetic parameters, the gas reaction path may be dominated either by adduct/amide formation path, or by TMG pyrolysis path, or by both. Although the reaction path varies with different kinetic parameters, the predicted growth rates change only slightly because the total transport rate of Ga-containing species to the substrate changes slightly with reaction paths. This explains why previous authors using different chemical models predicted growth rates close to the experiment values. By varying the pre-exponential factor for the amide trimerization, it is found that the more trimers are formed, the lower the growth rates are than the experimental value, which indicates that trimers are poor growth precursors, because of thermal diffusion effect caused by high temperature gradient. The effective order for the contribution of major species to growth rate is found as: pyrolysis species > amides > trimers. The study also shows that radical reactions have little effect on gas reaction path because of the generation and depletion of H radicals in the chain reactions when NH2 is considered as the end species.

中文翻译：

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反应动力学参数对 GaN MOVPE 生长反应路径建模的影响

摘要 在GaN MOVPE生长的反应输运过程建模中，气体反应动力学参数（活化能Ea和指前因子A）的选择具有较大的不确定性，导致气体反应路径和生长速率均存在不确定性。在这项研究中，对垂直旋转盘式反应器中 GaN MOVPE 生长的反应传输过程进行了数值模拟，其中主要反应路径的动力学参数不同。通过比较主要含 Ga 物种的摩尔浓度和生长速率，确定了动力学参数对气体反应路径的影响。结果表明，根据动力学参数的值，气体反应路径可能由加合物/酰胺形成路径，或由 TMG 热解路径，或由两者主导。尽管反应路径随不同的动力学参数而变化，但预测的生长速率仅略有变化，因为含 Ga 物种到衬底的总传输速率随反应路径略有变化。这解释了为什么以前的作者使用不同的化学模型预测的增长率接近实验值。通过改变酰胺三聚反应的指前因子，发现形成的三聚体越多，生长速率低于实验值，这表明三聚体是不良生长前体，这是由于高温引起的热扩散效应。温度梯度。发现主要物种对生长速率的贡献的有效顺序为：热解物种>酰胺>三聚体。