GaN（0001）缺陷表面诱导生长STO薄膜的理论研究

发布时间：2018-01-06 09:14

本文关键词：GaN（0001）缺陷表面诱导生长STO薄膜的理论研究　出处：《四川师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：本论文结合相关实验结果,并在已有计算的结果上进一步构造并计算了Ga N(0001)面上Ga空位缺陷对Ti O2分子、Sr O分子和Ba O分子的吸附。以及含有[10-10]和[11-20]两个方向缺陷的Ga N(0001)表面对Ti O2分子的吸附。计算机模拟的手段进行研究,具体应用MS软件中的castep模块计算,设计并优化了各个模型,在优化完成的构型上计算了态密度、密粒根电荷数等性质。首先,前期计算得到的最易形成的点缺陷为VGa点缺陷。我们在此优化好的VGa点缺陷表面上的不同位置放置了具有代表性的Ti O2分子、Sr O分子和Ba O分子。结果显示:Ti O2分子在VGa点缺陷面上的吸附能比其在干净表面上的吸附要弱,说明在同等条件下,Ti O2分子优先吸附于干净表面。以同样的条件计算的VGa点缺陷对Sr O分子和Ba O分子的吸附结果表明,VGa点缺陷对Sr O分子或者Ba O分子的吸附都比对Ti O2分子的吸附要容易。而干净表面对Ti O2分子的吸附要优于对其余两种分子的吸附。VGa点缺陷对Sr O分子或者Ba O分子的吸附结果表明,吸附后Sr-O键和Ba-O的成键方向都为[11-20]方向。这和实验生长方向是一致的。其次,我们设计并计算了含有[11-20]方向、[10-10]方向的Ga N(0001)面上的线缺陷。结果显示,[10-10]方向的线缺陷优化后的结果基本不变形,而[11-20]方向的线缺陷变形严重,推论是和缺失的Ga原子的个数有关(点缺陷的结果也是Ga空位缺陷变形严重,而N缺失则影响很小)。计算结果表明[11-20]方向的线缺陷没有[10-10]方向的线缺陷对Ti O2分子的吸附能大。最后,我们研究了Ga N(0001)面上的含有[10-10]、[11-20]方向的台阶缺陷。同样的[10-10]方向的线缺陷优化后的结果没有[11-20]方向的台阶缺陷变形严重。计算结果表明[11-20]方向的台阶缺陷比[10-10]方向的台阶缺陷对Ti O2分子的吸附能大。并且吸附后的最优吸附结果是Ti O2分子的两个O连线都几乎是[11-20]方向,这和实验生长方向是一致的。
[Abstract]:In this thesis, based on the experimental results and the calculated results, the Ga vacancy defects on the Ga surface have been further constructed and calculated for the TIO _ 2 molecules. Adsorption of Sr O and Ba O molecules. [10-10] and. [The adsorption of TIO _ 2 molecules on the surface of gan _ (0001) with two directional defects was studied by means of computer simulation. The castep module in MS software is applied to calculate, design and optimize each model, calculate the density of states and the charge number of dense root on the optimized configuration. Firstly. The most easily formed point defects obtained from the previous calculations are VGa point defects. We have placed representative TIO _ 2 molecules at different positions on the surface of the optimized VGa point defects. The results show that the adsorption energy of Sr O molecule and Ba O molecule on the defect surface of VGa point is weaker than that on the clean surface, which indicates that under the same conditions, the adsorption energy of Sr O molecule and Ba O molecule is weaker than that on the clean surface. TIO _ 2 molecules are preferentially adsorbed on clean surfaces. The adsorption of Sr _ O and Ba _ O molecules by VGa point defects calculated under the same conditions shows that TIO _ 2 molecules are adsorbed on clean surfaces. It is easier to adsorb Sr O or Ba O molecules by VGa point defects than to TIO 2 molecules, while Ti is adsorbed on clean surface. The adsorption of O2 molecule is better than that of the other two molecules. The bonding directions of Sr-O bond and Ba-O bond after adsorption are both. [This is consistent with the experimental growth direction. Secondly, we have designed and calculated the structures containing. [11-20] direction, [The line defects on the plane of 10-10] direction gan Nu 0001. The results show that, [The results of the optimization of the linear defects in the direction of 10-10 are basically non-deformable, while that of the linear defects is not deformed. [The line defects in the direction 11-20 are seriously deformed, and the corollary is that the number of missing Ga atoms is related to the number of missing Ga atoms. (the result of point defects is also that the defects of Ga vacancies are deformed seriously, while the effect of N deficiency is very small. [11-20] Line defects in the direction are not present. [The adsorption energy of TIO _ 2 molecules by linear defects in the direction of 10-10 is large. Finally, we have studied the adsorption energy of Ga _ (10) O _ (0001) on the surface of Ga _ (10) O _ (0001). [10-10], [11-20] directional step defects. The same. [The results of the optimization of the linear defects in the direction 10-10 are not available. [The step defects in the direction of 11-20 are seriously deformed. The calculation results show that. [Step defect ratio in the direction of 11-20. [The adsorption energy of TIO _ 2 molecule by step defect in 10-10 direction is high. The optimal adsorption result is that the O line of TIO _ 2 molecule is almost equal to that of TIO _ 2 molecule. [In the 11-20 direction, this is consistent with the experimental growth direction.
【学位授予单位】：四川师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB306;TB383.2

【相似文献】