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采用嵌入原子方法的原子间相互作用势,利用分子动力学模拟方法研究了Au/Cu(111)和Ag/Cu(111)体系的异质外延结构特征以及外延岛形貌和应变释放的演化过程.通过对比Au/Cu(111)和Ag/Cu(111)体系的异质外延结构及外延岛演化行为,揭示了导致Ag/Cu(111)体系中异质外延层形成Moiré结构的微观物理机理及其与外延体系的宏观物理特性之间的关系.研究结果显示,外延岛原子与基体表面原子之间的界面结合强度是形成Moiré结构的重要因素,异质外延体系的界面结合强度取决于二者的合金熔解热.当异质外延体系的合金熔解热为正值时,界面结合强度较弱,有利于Moiré结构的形成.同时,外延岛原子之间的相互作用决定着外延岛的面内弛豫行为,对Moiré结构的形成有一定的影响.外延岛的面内弛豫行为与外延层和基体之间的相对刚度有关,弹性模量较大的外延层具有较强的延展能力,对Moiré结构的形成有利.此外,Moiré结构的形成与外延岛的尺度有关,主要是外延岛边界原子的钉扎作用对外延岛内原子弛豫行为的约束作用的影响.
The molecular dynamics simulation method is used to study the heteroepitaxial structural characteristics of Au / Cu (111) and Ag / Cu (111) systems as well as the evolution of the morphology and strain release of the epitaxial island by using the intermolecular interaction potential of the embedded atomic method By comparing the heteroepitaxial structure of Au / Cu (111) and Ag / Cu (111) system and the evolution behavior of the epitaxial islands, the microscopic physical mechanism leading to the Moiré structure in the heteroepitaxial layer of Ag / Cu And its relationship with the macroscopic physical properties of the epitaxial system.The results show that the interface bonding strength between atoms of the epitaxial island and the surface of the substrate is an important factor in the formation of Moiré structure.The interfacial bonding strength of the heteroepitaxial system depends on two When the heat of fusion of the heteroepitaxial system is positive, the interface bonding strength is weak, which is favorable for the formation of Moiré structure.At the same time, the interaction between the atoms of the epitaxial islands determines the in-plane of the epitaxial island The relaxation behavior has certain influence on the Moiré structure.The in-plane relaxation behavior of the epitaxial island is related to the relative stiffness between the epitaxial layer and the substrate, and the epitaxial layer with larger elastic modulus has stronger extensibility, Advantageously Moiré structure is formed. In addition, the scale formed Moiré structure of epitaxial islands, mainly on the influence epitaxial island boundary pinning effect atoms epitaxial island atoms binding effect of the relaxation behavior.