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Computational Analysis of Low-Energy Dislocation Configurations in Graded Layers
Crystals ( IF 2.7 ) Pub Date : 2020-08-01 , DOI: 10.3390/cryst10080661
Daniele Lanzoni , Fabrizio Rovaris , Francesco Montalenti

Graded layers are widely exploited in semiconductor epitaxy as they typically display lower threading dislocation density with respect to constant-composition layers. However, strain relaxation occurs via a rather complex distribution of misfit dislocations. Here we exploit a suitable computational approach to investigate dislocation distributions minimizing the elastic energy in overcritical constant-composition and graded layers. Predictions are made for SiGe/Si systems, but the methodology, based on the exact (albeit in two dimensions and within linear elasticity theory) solution of the stress field associated with a periodic distribution of defects, is general. Results are critically compared with experiments, when possible, and with a previous mean-field model. A progressive transition from one-dimensional to two-dimensional distributions of defects when continuous linear grading is approached is clearly observed. Interestingly, analysis of the low-energy distribution of dislocations reveals close analogies with typical pile-ups as produced by dislocation multiplication.

中文翻译:

梯度层中低能位错构型的计算分析

梯度层在半导体外延中得到了广泛的利用,因为它们通常显示出比恒定组成层更低的螺纹位错密度。但是,应变松弛通过失配位错的相当复杂的分布而发生。在这里,我们利用一种合适的计算方法来研究位错分布,从而使超临界恒定组成层和渐变层中的弹性能最小化。对SiGe / Si系统进行了预测,但是该方法基于与缺陷的周期性分布相关的应力场的精确(尽管是二维的且在线性弹性理论之内),是通用的。在可能的情况下,将结果与实验以及以前的均场模型进行严格比较。当接近连续线性分级时,可以清楚地观察到缺陷从一维分布到二维分布的逐渐过渡。有趣的是,对位错的低能分布的分析揭示了与位错倍增产生的典型堆积的相似性。
更新日期:2020-08-01
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