温度对ZnO/Al2O3(0001)界面的吸附、扩散及生长初期模式的影响

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. 关键词： 扩散 薄膜生长 2O₃(0001)')" href="#">α-Al₂O₃(0001) ZnO

Temperature effect on the adsorption, diffusion and initial growth mode of ZnO/Al2O3(0001) from first principles

A heteroepitaxial growth model of the ZnO film on sapphire(0001) is simulated using the plane wave ultrasoft pseudo-potential method based on density functional theory. It is found that interfacial atoms have different diffusivity at 400,600 and 800℃. The temperature has a decisive effect on the surface and interface structures of ZnO/α-Al₂O₃(0001) and on the growth mode of ZnO thin films. In the whole process of the adsorption and growth of ZnO, the diffusivity of O atoms is higher than that of Zn, and the interlayer diffusion has an important role in the homogeneous growth of the thin films. There exist two growth modes of ZnO on sapphire (0001), which is further demonstrated by theoretical calculation. The growth mode at about 400℃ has the character of mainly spiral-twisted growth with Zn hexagonal symmetry structure, and it is favorable for forming the Zn-terminated surface. In the case of 600℃, a regular in-plane growth is observed, which facilitates the O-terminated surface of the nO thin film. It can be concluded from the calculation that the number of Zn vacancies is greater than that of O in the atomic layer of ZnO film near the α-Al₂O₃(0001) substrate surface.