Morphological evolution of SiGe layers
Morphological evolution of SiGe layers
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DOI：
10.1016/s0039-6028(03)00488-6
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发表时间：
2003-06-01
期刊：
影响因子：
1.9
通讯作者：
Portavoce, A
中科院分区：
文献类型：
--
作者：
Berbezier, I;Ronda, A;Portavoce, A
广泛的研究活动致力于非常小的连贯岛屿的自组装。然而，虽然岛的形成通常被广泛使用的S-K生长方案所描述，但基于动力学和热力学竞争效应的更复杂机制发生在Si1-xGex在Si（0 0 1）上的外延过程中。本文的目的是解释Si（0 0 1）上Si1-xGex岛的形成和演化。本文全面研究了Si（0 0 1）和Si（11 11 1）上Si1-xGex薄膜（x从0到1变化）的不同生长模式。结果以生长样品的动力学形态生长图的形式呈现。在（1 1 1）和（0 0 1）上分别区分出两种和四种生长状态。这些生长机制对应于不同程度的放松。特别是在Si（0 0 1）上观察到的四种状态对应于(i)状态1（二维层）没有松弛，（ii）状态ii（具有（1 0 5）个面的“小屋”岛）有15-20%的松弛，（iii）状态iii有20%和50%的松弛（分别在“小屋”和“圆顶”中），（iv）状态iv有50%和80%的松弛（双峰大小分布的“圆顶”）。生长样品的每一种生长状态特征也与生长样品经过长期退火后获得的特定平衡稳态形貌有关。在前两种状态（无应变松弛或小应变松弛）中，高应变Si1-xGex矿床的平衡形态对应于（1 ~ 5）面状岛屿。我们表明，这些岛屿是由压应力稳定的。一旦应变释放，（105）面消失，（1 1 3）和（1 1 1）面消失，“小屋”岛和“圆顶”岛之间发生一级过渡。(C) 2003 Elsevier Science B.V.版权所有
Extensive research activity has been devoted to self-assembly of very small coherent islands. However, while island formation is commonly described by a widely used S-K growth scheme, more complex mechanisms based on competitive effects of kinetics and thermodynamics take place during the epitaxy of Si1-xGex on Si(0 0 1). The aim of this paper is to explain the formation and the evolution of Si1-xGex islands on Si(0 0 1). The paper presents a comprehensive investiization of the different growth modes of Si1-xGex films (with x varying from 0 to 1) on Si(0 0 1) and Si(1 1 1). The results are presented in the form of kinetic morphological growth diagrams of as-grown samples. Two and four growth regimes are distinguished on (1 1 1) and (0 0 1) respectively. These growth regimes correspond to different levels of relaxation. In particular the four regimes observed on Si(0 0 1) correspond to (i) no relaxation in regime 1 (2D layer), (ii) 15-20% relaxation in regime II ("huts" islands with (1 0 5) facets), (iii) 20% and 50% relaxation in regime III (in "huts" and "domes" respectively) and (iv) 50% and 80% relaxation in regime IV ("domes" with bimodal size distribution). Every growth regime characteristic of as-grown sample is also associated with a specific equilibrium steady state morphology which is obtained after long-term annealing of the as-grown samples. In the two first regimes (no or small strain relaxation) the equilibrium morphology of highly strained Si1-xGex deposits corresponds to (1 0 5) faceted islands. We show that these islands are stabilised by the compressive stress. As soon as strain is released, (10 5) facets disappear at the expense of the (1 1 3) and (1 1 1) facets and first-order transition occurs between "huts" and "domes" islands. (C) 2003 Elsevier Science B.V. All rights reserved.