Theoretical analysis of strain relaxation mechanisms of heteroepitaxial layers

异质外延层应变弛豫机制的理论分析

基本信息

批准号：
10650074
负责人：
SHINTANI Kazuhito
金额：
$ 1.34万
依托单位：
The University of Electro-Communications
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

1 The anisotropic linear stability analysis of surface undulations of semiconductor heteroepitaxial layers was performed. Numerical results for SiィイD21-xィエD2GeィイD2xィエD2/Si systems show that the free energy change for the <100> surface undulations is greater than for the <110> undulations, which means surface undulations are likely to be formed in the <100> directions, that the present theory predicts the critical wavelength for the SiィイD20.82ィエD2GeィイD20.18ィエD2/Si system at 444nm which is in good agreement with the experimental value 44Onm, and that the main mechanism of the strain relaxation is the formation of surface undulations at the Ge fraction greater than 0.5 while it is the misfit dislocation generation at the Ge fraction less than 0.5.2 The molecular dynamics simulations were performed for the dislocation generation from the surface of Si thin films. The Stillinger-Weber potential was used. The effects of surface steps and temperature on the change of the atomic structures are … More investigated. The simulation results show that at the temperatures 500K and 1000K, the energy decrease always occurs if the strain of the system exceeds a critical value whether there exists a surface step or not and whether the strain is compressive or tensile, that the energy decrease occurs due to the formation of (111) stacking faults either at an arbitrary point on the surface if there is no step or at the surface step if there is one, and that both the SィイD2AィエD2 and SィイD2BィエD2 steps can become generation points of stacking faults and the critical strain for the former is smaller from 1% to 2% than for the latter.3 The atomistic calculations of the strain profiles within GaAs/InAs/GaAs pyramidal quantum dot structures were performed. The most stable atomic structures were obtained by the conjugate gradient minimization of the system energy expressed in terms of the Stillinger-Weber potential. The results show that there arises tensile strain just above the top of the island, which causes the vertical self-ordering of the stacked dots, that the larger the thickness of the wetting layer, the greater the magnitude of the tensile strain, and that the present results are in good agreement with those obtained by the inclusion theory. Less

1对半导体杂质层层的表面起伏的各向异性线性稳定性分析。 Numerical results for Sii D21-xie D2Ge D2xie D2/Si systems show that the free energy change for the <100> surface undulations is greater than for the <110> undulations, which means surface undulations are likely to be formed in the <100> directions, that the present theory predictions the critical wavelength for the Sii D20.82IeD2GeIID20.18IeD2/Si system at 444nm which is in good与实验值44ONM一致，并且应变弛豫的主要机制是在GE级分的表面起伏的形成大于0.5，而在GE分数下的不合适脱位产生小于0.5.5.分子动力学模拟是从SI薄膜表面产生的分子动力学模拟。使用了Stillinger-Weber电位。表面步骤和温度对原子结构变化的影响。模拟结果表明，在500K和1000K的温度下，如果系统的应变超过临界值，能量下降始终发生，无论是否存在表面步骤，以及应变是否是压缩还是应变，则能量下降，如果在（111）的表面上或在表面上堆叠的情况下，则在表面上堆叠的台阶和在Surface上的堆叠率是不存在的。 SIE D2BIE D2步骤可以成为堆叠断层的生成点，而前者的临界应变比后者的临界应变小于1％至2％。3进行GAAS/INAS/INAS/GAAS锥体量量子点结构内的应变曲线的原子计算。最稳定的原子结构是通过根据stillinger-weber电位表达的系统能量的结合梯度最小化获得的。结果表明，在岛上的顶部上方出现拉伸应变，从而导致堆叠点的垂直自我排序，即润湿层的厚度越大，拉伸应变的幅度越大，并且本结果与包含理论获得的结果非常吻合。较少的