冷速对液态GaAs快速凝固过程中微观结构的影响

Effect of Cooling Rates on Microstructures During Solidification of Liquid GaAs

采用分子动力学方法对液态GaAs在六种不同冷速下的快速凝固过程进行模拟,并采用双体分布函数、平均配位数、键角分布函数、二面角分布和可视化等方法对凝固过程的微观结构变化进行分析。结果表明:凝固过程中部分As原子发生偏聚,冷却后形成γ砷(简单立方结构As8),当冷速为1×10^(10) K/s和2×10^(10) K/s时,富Ga区域主要是以闪锌矿和纤锌矿为主的晶体结构;当冷速高于5×10^(10) K/s时,富Ga区域形成以Ga-Ga-Ga和Ga-As-Ga三元环结构为主的非晶无规网络结构。

A simulation study was performed for the effects of different cooling rates on microstructure during solidification of liquid GaAs by means of molecular dynamics method.Through the pair distribution function,the average coordination number,the bond angle distribution function,the dihedral angle distribution and visualization method were used to analyze the variations of microstructure during the solidification process.Results show that part of the As atoms converged and formedγ-As（simple cubic structure As8）,when the cooling rate is 1×10^（10） K/s and 2×10^（10） K/s,the Ga enrichment area are mainly composed of zinc-blende and wurtzite crystal structure;when the cooling rate is higher than 5×10^（10） K/s,the Ga enrichment area are mainly formed of amorphous structure to give priority to the structure of Ga-As-Ga and Ga-Ga-Ga ternary ring.