反应动力学参数变化对MOVPE生长GaN的反应路径模拟的影响
发布时间：2019-05-16 17:22
【摘要】：在金属有机化学气相外延(MOVPE)生长GaN薄膜的反应-输运过程数值模拟中,反应动力学参数(活化能和指前因子)的选取存在很大的不确定性,从而导致不同的气相反应路径和生长速率.本文对前人采用的反应动力学参数的偏差做了归纳总结,讨论了偏差的来源.在此基础上,本文对垂直转盘式MOVPE反应器生长GaN的反应-输运过程进行数值模拟研究.模拟改变不同的反应动力学参数组合,包括加合物的生成和可逆分解的指前因子、加合物不可逆分解生成氨基物的活化能和指前因子以及三聚物生成的指前因子.通过分析主要含Ga物质的摩尔浓度和对应的生长速率的变化,研究上述反应动力学参数变化对GaN生长反应路径的模拟结果的影响.研究的主要结论如下:(1)不同的指前因子和活化能导致不同的反应路径和生长速率的差异,而热解路径比起加合路径能够更有效地提高生长速率.(2)在不考虑三聚物反应时,预测的生长速率值都与实验值接近.原因在于,输运限制的生长速率取决于含Ga粒子的输运速率,不同的反应路径对含Ga粒子的影响此消彼长,但到达衬底的含Ga粒子的总量变化不大,这也很好地解释了不同文献采用不同的动力学参数模拟都与实验基本吻合的原因.(3)改变三聚物反应的指前因子发现,由于热泳力对大分子的排斥作用,三聚物对生长的贡献很小,生成的三聚物越多,与实验的误差越大.模拟结果澄清了前人在模拟MOVPE生长GaN的反应-输运过程中存在的一些问题,并加深了对GaN生长机理的了解.
[Abstract]:In the numerical simulation of reaction-transport process of GaN thin films grown by metal organic chemical vapor phase epitaxial (MOVPE), there is great uncertainty in the selection of reaction kinetic parameters (activation energy and preexponential factor). This leads to different gas phase reaction paths and growth rates. In this paper, the deviation of the reaction kinetic parameters adopted by the predecessor is summarized, and the source of the deviation is discussed. On this basis, the reaction-transport process of GaN growth in vertical turntable MOVPE reactor was studied by numerical simulation. Different combinations of reaction kinetic parameters were simulated, including the formation of adduct and the pre-exponential factor of reversible decomposition, the activation energy and preexponential factor of irreversible decomposition of adduct to amino substance, and the preexponential factor of trimer formation. By analyzing the molar concentration of Ga and the corresponding growth rate, the effect of the above kinetic parameters on the simulation results of GaN growth path was studied. The main conclusions are as follows: (1) different preexponential factors and activation energy lead to different reaction paths and growth rates. The pyrolysis path can increase the growth rate more effectively than the addition path. (2) when the trimer reaction is not considered, the predicted growth rate is close to the experimental value. The reason is that the growth rate of transport restriction depends on the transport rate of Ga particles, and the influence of different reaction paths on Ga particles increases or decreases, but the total amount of Ga particles arriving on the substrate does not change much. This also explains why the simulation of different kinetic parameters in different literatures is basically consistent with the experiment. (3) it is found that due to the rejection of macromolecules due to the repulsive effect of thermal swimming force, it is found that the preexponential factor of trimer reaction is changed. The contribution of trimer to growth is very small, and the more trimer is formed, the greater the error with the experiment. The simulation results clarify some problems existing in the reaction-transport process of simulating the growth of GaN by MOVPE, and deepen the understanding of the growth mechanism of GaN.
【作者单位】： 江苏大学能源与动力工程学院;
【基金】：国家自然科学基金(批准号:61474058) 江苏省普通高校研究生科研创新计划(批准号:CXLX11_0573)资助项目
【分类号】：TN304.2
，
本文编号：2478440
[Abstract]:In the numerical simulation of reaction-transport process of GaN thin films grown by metal organic chemical vapor phase epitaxial (MOVPE), there is great uncertainty in the selection of reaction kinetic parameters (activation energy and preexponential factor). This leads to different gas phase reaction paths and growth rates. In this paper, the deviation of the reaction kinetic parameters adopted by the predecessor is summarized, and the source of the deviation is discussed. On this basis, the reaction-transport process of GaN growth in vertical turntable MOVPE reactor was studied by numerical simulation. Different combinations of reaction kinetic parameters were simulated, including the formation of adduct and the pre-exponential factor of reversible decomposition, the activation energy and preexponential factor of irreversible decomposition of adduct to amino substance, and the preexponential factor of trimer formation. By analyzing the molar concentration of Ga and the corresponding growth rate, the effect of the above kinetic parameters on the simulation results of GaN growth path was studied. The main conclusions are as follows: (1) different preexponential factors and activation energy lead to different reaction paths and growth rates. The pyrolysis path can increase the growth rate more effectively than the addition path. (2) when the trimer reaction is not considered, the predicted growth rate is close to the experimental value. The reason is that the growth rate of transport restriction depends on the transport rate of Ga particles, and the influence of different reaction paths on Ga particles increases or decreases, but the total amount of Ga particles arriving on the substrate does not change much. This also explains why the simulation of different kinetic parameters in different literatures is basically consistent with the experiment. (3) it is found that due to the rejection of macromolecules due to the repulsive effect of thermal swimming force, it is found that the preexponential factor of trimer reaction is changed. The contribution of trimer to growth is very small, and the more trimer is formed, the greater the error with the experiment. The simulation results clarify some problems existing in the reaction-transport process of simulating the growth of GaN by MOVPE, and deepen the understanding of the growth mechanism of GaN.
【作者单位】： 江苏大学能源与动力工程学院;
【基金】：国家自然科学基金(批准号:61474058) 江苏省普通高校研究生科研创新计划(批准号:CXLX11_0573)资助项目
【分类号】：TN304.2
，
本文编号：2478440
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