Theoretical analysis of strain relaxation mechanisms of heteroepitaxial layers

1.对半导体异表皮层表面补偿的异向线性稳定性分析进行了分析。Numerical results for Si-D21-x y-D2Ge-D2x y-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-D20.82-D2Ge-D20.18-D2/Si system at 444nm which is in good agreement with the experimental value 44Onm，而且，由于应变放松的主要机制是在Ge片段大于0.5时，它是在Ge片段较少的地方产生的不合适的分散一代。than 0. 5. 2 The molecular dynamics simulations were performed for the dislocation generation from the surface of Si thin films。Stillinger-Weber的潜力被使用了。表面步骤和温度对原子结构变化的影响 ... More 被调查的。模拟结果显示，在温度500 K和1000 K时，如果系统的应变系统表现出临界值，如果存在表面步骤或不存在，以及如果应变是压缩的或紧张的，能量的退化导致了它的形成（111）如果表面上没有步骤，或者如果表面上有一个步骤，或者如果表面上有一个步骤，而且两者都可以成为堆叠故障的一代点，以及对于前一代来说，关键的应变从1%到2%都很小。than for the latter. 3 The atomistic calculations of the strain profile in GaAs/InAs/GaAs pyramidal Quantum dot structures were performed.“最稳定的原子结构是由腐蚀性梯度最小化的系统能量在Stillinger-Weber潜力的术语中产生的。”结果显示了arises tensile strain仅高于岛屿的顶部，导致了堆叠点的垂直自排序，即湿层的更大厚度，即张力strain的更大强度，以及目前的结果是与包含理论所获得的良好协议有关的良好结果。Less（低）

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