Barbisan Luca, Marzegalli Anna, Montalenti Francesco
Department of Materials Science, L-Ness and Università degli Studi di Milano-Bicocca, Via R. Cozzi 55, 20125, Milan, Italy.
Department of Physics, L-Ness and Politecnico di Milano, via Anzani 42, 22100, Como, Italy.
Sci Rep. 2022 Feb 25;12(1):3235. doi: 10.1038/s41598-022-07206-3.
Heteroepitaxial films of Ge on Si(001) are receiving wide attention due to several possible applications in micro- and opto-electronics. Understanding the dynamic behavior of linear defects, such as dislocations, is key. They are unavoidably present in such systems due to the lattice mismatch between the two materials, and can directly influence devices performances. It has been experimentally demonstrated more than fifteen years ago that a suitable choice of the growth parameters allows for the formation of a nicely ordered net of [Formula: see text] dislocations at the Ge/Si interface, improving the overall film quality and strain relaxation uniformity. Atomic-scale details on the set of mechanisms leading to such an outcome are however still missing. Here we present a set of classical molecular dynamics simulations shedding light on the full set of microscopic processes driving to the experimentally observed array of linear defects. This includes simple gliding of [Formula: see text] dislocations and vacancy-promoted climbing and gliding. The importance of the particular experimental conditions, involving a low-temperature stage followed by an increase in temperature, is highlighted.
由于在微电子和光电子领域的多种潜在应用，硅（001）衬底上的锗异质外延薄膜受到了广泛关注。了解诸如位错等线性缺陷的动态行为是关键所在。由于这两种材料之间的晶格失配，这些缺陷在这类系统中不可避免地存在，并且会直接影响器件性能。早在十五年前就已通过实验证明，适当选择生长参数能够在锗/硅界面形成排列良好的[公式：见原文]位错网络，从而提高整体薄膜质量和应变弛豫均匀性。然而，导致这一结果的一系列机制的原子尺度细节仍不明确。在此，我们展示了一组经典分子动力学模拟，揭示了导致实验观测到的线性缺陷阵列的完整微观过程。这包括[公式：见原文]位错的简单滑移以及空位促进的攀移和滑移。文中强调了特定实验条件的重要性，该条件包括一个低温阶段，随后温度升高。
