The influence of the polarity of ceramic substrates on the structural evolution of thin metal films during annealing at elevated temperatures is investigated, including the competing processes of solid state dewetting (SSD) and grain growth, as well as the atomic structure of the epitaxial interface. For this purpose, Au thin films on polar O-ZnO$\left(000\overline{1}\right)$$\left(000\overline{1}\right)$ and Zn-ZnO$\left(0001\right)$$\left(0001\right)$ surfaces are annealed at elevated temperatures and times. Whereas SSD dominates on the O-terminated surface, pronounced grain growth is observed on the Zn-terminated surface. The texture analysis revealed that up to 600°C, both samples exhibit a fiber texture with slightly dominating Au(111)[110] || ZnO(0001)[$11\overline{2}0$$11\overline{2}0$] orientation relation (OR 2). At 800°C, Au on Zn-ZnO exhibits a transformation to a mazed bicrystal structure with Au(111)[110] || ZnO(0001)[$10\overline{1}0$$10\overline{1}0$] orientation relation (OR 1). Comparison of various interface structures in density-functional theory (DFT) indicates that atomically sharp interfaces between the Au(111) films and the ideal bulk-truncated polar ZnO surfaces are energetically favored for both substrate polarities in excellent agreement with atomically resolved electron microscopy. Due to the larger period of the coincidence site lattice in OR 2, the corresponding interface can be described as semi-coherent with clearly separated misfit dislocations. In contrast, the much smaller period of the (approximate) coincidence site lattice in OR 1 leads to a largely incoherent interface with local reconstructions. However, in the experimental situation, even a small rotational deviation from the perfect OR 1 can introduce an interfacial screw dislocation network superimposed on the incoherent interface structure, effectively making the interface semi-coherent.

中文翻译：

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衬底极性对 ZnO 表面 Au 薄膜的热稳定性、晶粒生长和原子界面结构的影响


研究了陶瓷衬底极性对高温退火过程中金属薄膜结构演变的影响，包括固态去湿 （SSD） 和晶粒生长的竞争过程，以及外延界面的原子结构。为此，极性 O-ZnO$（000\bar{1}）$ 和 Zn-ZnO$（0001）$ 表面在高温和时间下退火。SSD 在 O 封端表面上占主导地位，而在 Zn 封端表面上观察到明显的晶粒生长。 质构分析显示，在600°C的温度下，两个样品都表现出纤维质构，其中Au（111）略占主导地位[110] ||氧化 $\left(0001\right)$ 锌 [$11\stackrel{}{\mathrm{}}\mathrm{}$ 2 ̄ 0] 方向关系 （OR 2）。在 800°C 时，Zn-ZnO 上的 Au 表现出向 Au（111） 的错化双晶结构转变[110] ||氧化锌（0001）[$10\bar{1}0$] 方向关系 （OR 1）。密度泛函理论 （DFT） 中各种界面结构的比较表明，Au（111） 薄膜和理想的体截短极性 ZnO 表面之间的原子尖锐界面在能量上有利于两种衬底极性，与原子分辨电子显微镜非常一致。由于 OR 2 中重合位点晶格的周期较大，相应的界面可以描述为半相干的，具有明显分离的错拟合位错。相比之下，OR 1 中（近似）重合位点晶格的较小周期导致与局部重建的界面在很大程度上不连贯。 然而，在实验情况下，即使与完美 OR 1 的旋转偏差很小，也会在不相干的界面结构上引入一个界面螺旋位错网络，有效地使界面半相干。