立式HVPE生长GaN的计算机模拟

发布时间：2018-05-24 07:03

  本文选题：氢化物气相外延 + GaN　； 参考：《南京邮电大学》2015年硕士论文

【摘要】：本文基于计算流体力学(CFD)原理,运用流体力学相关知识,采用有限元分析软件对自制的立式氢化物气相外延(HVPE)系统制备GaN材料进行了数值模拟研究。采用CFD软件模拟GaN的生长一方面能够有效节省实验成本,为制备高质量GaN的腔体优化提供优化基础,另一方面可以不受传统热力学和动力学机制的束缚,预测整个衬底上方GaN的生长情况,对实际过程中对GaN的生长有一定指导意义。对反应气体出气管口到衬底的距离是否影响衬底上方GaCl和NH3的摩尔浓度分布进行了二维模拟计算。通过设定多组实验模型,不同模型中衬底到出气口距离并不相同,对比不同距离下GaN的生长速率和均匀性的对比来得到最佳距离。通过对比得到当衬底高度15mm时有利于反应气体的分布。通过建立二维模型来研究出气管口口径大小的改变是否影响衬底上方GaCl的摩尔浓度分布、NH3的摩尔浓度分布和Ga N的生长情况。整个优化过程分为两步,首先设定N2的内径是固定的,改变NH3和GaCl的出气口内径大小来得到一组最优化解,然后单独改变N2的出口内径来得到N2的最后化解。通过计算分析得到当GaCl的出口内径为12mm、NH3出口的内径为43mm和N2出气口内径为76mm时,此时得到GaN薄膜均匀性得到了很大提高。单独调整GaCl出气管口到衬底的距离来进一步优化腔体。当GaCl出气管口距离衬底过近时会阻挡一部分NH3在衬底中间位置的扩散,当距离过远时,会使一部分NH3扩散到GaCl出气管口,这两种情况对于GaN的生长是十分不利的。设置不同的GaCl出气管口到衬底距离来分析对应GaN的生长情况,通过模拟计算得到当GaCl出气管口到衬底的距离为17mm时此时均匀性得到进一步提高,相对均匀性达到4.2%。
[Abstract]:Based on the principle of computational fluid dynamics (CFD) and using the knowledge of hydrodynamics, the finite element analysis software is used to simulate the preparation of the self-made vertical hydride vapor phase epitaxy (HVPE) system for the preparation of GaN materials. Using CFD software to simulate the growth of GaN, the experimental cost can be effectively saved and the cavity of high quality GaN is prepared. Optimization provides the basis for optimization. On the other hand, the growth of GaN above the whole substrate can be predicted without the constraints of traditional thermodynamics and dynamics. It has certain guiding significance for the growth of GaN in the actual process. Whether the distance between the outlet of the gas outlet tube and the substrate affects the molar concentration distribution of the GaCl and NH3 above the substrate. Two dimensional simulation calculation. By setting a number of experimental models, the distance between the substrate and the outlet is not the same in the different models. The optimum distance is obtained by comparing the growth rate and uniformity of GaN under different distances. By contrast, the distribution of the reaction gas is favorable when the height of the substrate is 15mm. A two-dimensional model is established to study the trachea. Whether the change of the size of the aperture affects the molar concentration distribution of GaCl above the substrate, the distribution of the molar concentration of NH3 and the growth of Ga N. The whole optimization process is divided into two steps. First, the internal diameter of N2 is fixed, and the size of the outlet diameter of NH3 and GaCl is changed to get a group of optimal solutions, and then the exit inner diameter of N2 is changed separately. To the final resolution of N2, it is obtained that when the internal diameter of the GaCl is 12mm, the inner diameter of the NH3 outlet is 43mm and the inner diameter of the N2 outlet is 76mm, the uniformity of the GaN film is greatly improved at this time. The distance of the GaCl outlet pipe to the substrate is further optimized. When the GaCl exits are too close to the substrate, the GaN film will be more close to the substrate. Blocking a part of the diffusion of NH3 in the middle of the substrate, when the distance is too far, will spread a part of the NH3 to the outlet of the GaCl outlet. These two cases are very unfavorable to the growth of GaN. Set the different GaCl outlet to the substrate distance to analyze the growth of the corresponding GaN, through the simulation calculation, when the outlet of the GaCl outlet pipe to the substrate is obtained. When the distance is 17mm, the homogeneity is further improved and the relative homogeneity is 4.2%..
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.05

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