Si晶体中60°位错运动的分子动力学研究

Molecular Dynamics Study on the 60° Dislocation Motion in Si Crystal

在S i晶体中建立了60°位错偶极子模型并通过Parrinello-Rahm an方法施加剪应力,使用分子动力学方法研究了60°位错在不同的温度和剪应力作用下的运动特性。观察到了位错速度与剪应力成正比关系;而温度对位错速度的影响,随着外加剪应力的不同呈现出三种趋势:(1)低剪应力作用下,位错速度与温度成正比关系;(2)剪应力达到0.6GPa附近时,位错速度与温度呈反比关系,声子拖动效应开始起作用;(3)当剪应力达到2GPa时,位错速度稳定在某一特定值,不再明显随温度的变化而变化。

The motion characteristics of Si 60° dislocations at the differential temperatures and shear stresses applied by Parrinello-Rahman method were simulated by utilizing molecular dynamics （MD） model. It is found that the 60° dislocations velocity is directly proportional to the applied shear stress, and three different tendencies associated with the dislocation velocity affected by applied shear stress at the differential temperatures are presented：（ 1 ） The velocity increases as the temperature increases when the shear stress is much lower than 0.6GPa; （2） The dislocation velocity decreases as the temperature increases when shear stress is around 0.6GPa. The phonon drag effect takes place in this case; （3） The dislocation velocity becomes insensitive to the system temperature when the shear stress approaches to 2GPa.