失配性质对二维失配铝膜结构及位错形成的影响

Effects of misfit characters on the structure and dislocation of two-dimensional misfit aluminium film

采用三维分子动力学模拟方法,使用Ercolessi和Adams建立的嵌入原子法(EAM)多体势函数,模拟了二维失配铝膜晶体中失配位错的形成过程,研究了失配性质对二维失配铝膜结构及其形核机制的影响.结果显示:同等条件下,负失配度的临界厚度小于正失配度情况;负失配度较易出现失配位错;负失配度下位错的形成始于表层一个倒三角锥形的间隙原子团;正失配度下位错的形成始于表层原子的畸变区;结构稳定后,负失配度体系在表层挤出局部原子层;正失配度体系会出现塌陷.

The influences of the misfit nature on the structure of two-dimensional aluminum film and its nucleation mechanism are studied by using the methods of three-dimensional molecular dynamics simulation and many-body potential function of embedded atom method（EAM） created by Ercolessi and Adams,and simulating the processes of misfit dislocations in two-dimensional mismatch aluminum film crystal.The result shows that under the same conditions,the critical thickness of negative mismatch is smaller than that of positive mismatch;the negative mismatch is prone to misfit dislocation;the negative misfit dislocation is formed from gap atomic group in a downward-pointing triangle on its surface;the positive misfit dislocation is made from distorted region on atomic surface;when the structure is stable,the negative mismatching system will extrude local atomic layer on its surface;the positive mismatching system will start to collapse.