论文部分内容阅读
构建了一个ZnO沉积在α-Al2O3(0001)表面生长初期的模型,采用基于密度泛函理论的平面波超软赝势法进行了动力学模拟.发现在400,600和800℃的条件下界面原子有不同的扩散能力,因此温度对ZnO/α-Al2O3(0001)表面界面结构以及ZnO薄膜生长初期模式有决定性的影响.在整个ZnO吸附生长过程中,O原子的扩散系数大于Zn原子的扩散系数,O原子的层间扩散对薄膜的均匀生长起着重要作用.进一步从理论计算上证实了ZnO在蓝宝石(0001)上两种生长模式的存在,400℃左右生长模式主要是Zn螺旋扭曲生长,具有Zn六角平面对称特征,且有利于Zn原子位于最外表面.600℃左右呈现为比较规则的层状生长,且有利于O原子位于最外表面.模拟观察到在ZnO薄膜临近Al2O3基片表面处,Zn的空位缺陷明显多于O的空位缺陷.
A model of ZnO deposition at the initial stage of α-Al2O3 (0001) surface was constructed, and the dynamic simulation was carried out by plane wave super soft pseudopotential method based on density functional theory. It was found that the interface atoms were different under the conditions of 400, 600 and 800 ℃ (0001) surface morphology and the initial growth mode of ZnO thin films have a decisive influence on the growth of ZnO films. The diffusion coefficient of O atoms is larger than the diffusivity of Zn atoms in the whole ZnO adsorption growth. O The interlayer diffusion of atoms plays an important role in the uniform growth of the films.Further theoretical calculations confirm the existence of two growth modes of ZnO on sapphire (0001). The growth modes at 400 ℃ are mainly Zn helical twisting growth with Zn Hexagonal plane symmetry, and is conducive to the Zn atom located on the outermost surface.At about600 ℃, a more regular layered growth is observed, and the O atom is located on the outermost surface.It is found that at the surface of the ZnO film adjacent to the Al2O3 substrate, Zn vacancy defects significantly more than O vacancy defects.