Abstract Structural features of Si 1 − x − y Ge x Sn y alloy layers grown on Si by molecular-beam epitaxy are studied. These layers with the thickness of 2.0 nm, the nominal Ge composition of x 0 ≈ 0.3, and the Sn-content of y ≈ 2–6 at.% have been grown at low temperatures (100–150 °C). We have used high-resolution transmission electron microscopy to analyze atomic structure of grown layers and Raman spectroscopy to evaluate the real Ge-content x from the observed optical phonon frequencies. It is found that the x value coincides with the nominal one at low Sn-content (2–3 at.%), and when it is increased (y ≥ 5 at.%), the decomposition of alloys into two fractions occurs. One of them is enriched by Ge with x up to 0.6 and the other fraction is Si-enriched. It is shown that the observed decomposition is Sn-induced and related to increase in Ge adatoms mobility in the growth process. This mechanism is similar to that theoretically predicted by Venezuela and Tersoff (Phys. Rev. 58 , 10871 (1998)) for the case of high growth temperature.

中文翻译：

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Sn – 通过分子束外延在 Si 上生长的 SiGeSn 合金的诱导分解

摘要 研究了通过分子束外延在Si上生长的Si 1 - x - y Ge x Sn y 合金层的结构特征。这些厚度为 2.0 nm、标称 Ge 组成为 x 0 ≈ 0.3、Sn 含量为 y ≈ 2–6 at.% 的层是在低温（100–150 °C）下生长的。我们使用高分辨率透射电子显微镜来分析生长层的原子结构和拉曼光谱，以从观察到的光学声子频率评估真实的 Ge 含量 x。发现 x 值与低 Sn 含量（2-3 at.%）时的标称值一致，当它增加时（y ≥ 5 at.%），合金分解成两部分。其中一个被 Ge 富集，x 高达 0.6，另一部分是富硅。结果表明，观察到的分解是 Sn 诱导的，并且与生长过程中 Ge 吸附原子迁移率的增加有关。这种机制类似于委内瑞拉和特尔索夫 (Phys. Rev. 58, 10871 (1998)) 在高生长温度的情况下理论上预测的机制。