CNRS, IM2NP, Faculté des Sciences de Saint-Jérôme case 142, 13397 Marseille, France.
Aix-Marseille University, IM2NP, Faculté des Sciences de Saint-Jérôme case 142, 13397 Marseille, France.
Beilstein J Nanotechnol. 2014 Dec 9;5:2374-82. doi: 10.3762/bjnano.5.246. eCollection 2014.
The Stranski-Krastanov growth of Ge islands on Si(001) has been widely studied. The morphology changes of Ge islands during growth, from nucleation to hut/island formation and growth, followed by hut-to-dome island transformation and dislocation nucleation of domes, have been well described, even at the atomic scale, using techniques such as scanning tunneling microscopy and transmission electron microscopy. Although it is known that these islands do not consist of pure Ge (due to Si/Ge intermixing), the composition of the Ge islands is not precisely known. In the present work, atom probe tomography was used to study the composition of buried dome islands at the atomic scale, in the three-dimensional space. The core of the island was shown to contain about 55 atom % Ge, while the Ge composition surrounding this core decreases rapidly in all directions in the islands to reach a Ge concentration of about 15 atom %. The Ge distribution in the islands follows a cylindrical symmetry and Ge segregation is observed only in the {113} facets of the islands. The Ge composition of the wetting layer is not homogeneous, varying from 5 to 30 atom %.
硅（001）衬底上锗岛的斯特兰斯基-克拉斯坦诺生长过程已被广泛研究。利用扫描隧道显微镜和透射电子显微镜等技术，可以很好地描述锗岛在生长过程中的形貌变化，从成核到丛岛形成和生长，再到丛岛到穹顶岛的转变以及穹顶的位错成核，甚至在原子尺度上。尽管众所周知这些岛不包含纯锗（由于 Si/Ge 互混），但锗岛的组成并不确切。在本工作中，原子探针层析术被用于在三维空间中研究埋层穹顶岛的原子尺度组成。岛的核心被证明含有约 55 原子%的锗，而围绕这个核心的锗组成在岛中的各个方向迅速下降，达到约 15 原子%的锗浓度。岛中的锗分布呈现圆柱对称性，并且只在岛的{113}面观察到锗的偏析。润湿层的锗组成不均匀，从 5 到 30 原子%不等。
