GaAs晶体在不同应变下生长过程的分子动力学模拟

Molecular dynamics simulations of GaAs crystal growth under different strains

GaAs晶体的高质量生长对于制造高性能高频微波电子器件和发光器件具有重要意义.本文通过分子动力学方法对GaAs晶体沿[110]晶向的诱导结晶进行模拟,并采用最大标准团簇分析、双体分布函数和可视化等方法研究应变对生长过程和缺陷形成的影响.结果表明,不同应变条件下GaAs晶体的结晶过程发生显著变化.在初始阶段,施加一定拉应变和较大的压应变后,体系的晶体生长速率发生降低,且应变越大,结晶速率越低.此外,随着晶体的生长,体系形成以{111}小平面为边界的锯齿形界面,生长平面与{111}小平面之间的夹角影响固液界面的形态,进而影响孪晶的形成.施加拉应变越大,此夹角越小,形成孪晶缺陷越多,结构越不规则.同时,体系中极大部分的位错与孪晶存在伴生关系,应变的施加可以抑制或促进位错的形核,合适的应变甚至可以使晶体无位错生长.本文从原子尺度上研究GaAs的微观结构演化,可为晶体生长理论提供理论指导.

The high-quality growth of GaAs crystals is extremely essential for the fabrication of high-performance high-frequency microwave electronic devices and light-emitting devices.In this work,the molecular dynamics(MD)simulation is used to simulate the induced crystallization of GaAs crystal along the[110]orientation.The effects of strain on the growth process and defect formation are analyzed by the largest standard cluster analysis,the pair distribution function,and visualization analysis.The results indicate that the crystallization process of GaAs crystal changes significantly under different strain conditions.At the initial stage,the crystal growth rate of the system decreases after a certain tensile strain and a large compressive strain have been applied,and the greater the strain,the lower the crystallization rate is.In addition,as the crystal grows,the system forms a zigzag interface bounded by the{111}facet,and the angle between the growth plane and the{111}facet affects the morphology of the solid-liquid interface and further affects the formation of twins.The larger the applied tensile strain and the smaller the angle,the more twin defects will form and the more irregular they will be.At the same time,a large proportion of the dislocations in the system is associated with twins.The application of strain can either inhibit or promote the nucleation of dislocations,and under an appropriate amount of strain size,crystals without dislocations can even grow.The study of the microstructural evolution of GaAs on an atomic scale provides a reference for crystal growth theory.