异质结构的应变和应力分布模型研究

基于组合杆的平衡条件，分别建立了晶格失配、热失配以及由两者共同导致的异质结构应变 和应力分布模型，并获得了异质结构的晶格失配应变、热失配应变、弯曲应变以及曲率半径 的分析解. 同时，运用所建的模型，计算了HgCdTe/CdZnTe异质结构的应变和应力分布.结果 表明：应力最大值均在界面处，而中性面仅是材料厚度和弹性参数的函数，与晶格失配、晶 格弛豫、热失配等参数无关，且该异质结构的曲率半径是衬底厚度的函数，随衬底厚度的减 小而减小，而要保证HgCdTe/CdZnTe器件在液氮温度下不发生断裂，衬底的厚度必须大于临界值. 关键词： 异质结构 应变分布模型 应力分布模型 晶格失配

Study on models of strain and stress distribution in heterostructures

Based on the equilibrium of combined girders, a set of models for the strain a nd stress distributions in heterostructures introduced by lattice mismatch, ther mal mismatch and the combination of the two factors are set up, and the analyti c solutions, including lattice mismatch strain, thermal mismatch strain, bending strain and the radius of curvature of the system, are also given. Furthermore, by using the models given here, strain and stress distributions in HgCdTe/CdZnTe heterostructures are calculated. The results show that both the maximum stress in HgCdTe films and the maximum stress in CdZnTe always appear at the interface between them, and that the neutral axis as a function of thickness and elastic parameters in the heterostructures are not related to lattice mismatch, lattice relaxation, thermal mismatch, and so on. In addition, the radius of curvature of HgCdTe/CdZnTe decreases with decreasing thickness of CdZnTe. In order to avoid cracking of HgCdTe/CdZnTe device at 77K, the thickness of CdZnTe must b e larger than the limited value.