Ordered structures in SixGe1-x alloy thin films.
Ordered structures in SixGe1-x alloy thin films.
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SixGe1-x 合金薄膜中的有序结构。
DOI：
10.1103/physrevb.51.10947
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Houghton
中科院分区：
文献类型：
--
作者：
Tischler;Budai;Jesson;Ereş;Zschack;Baribeau;Houghton
用四圆X射线衍射方法研究了Si（001）衬底上外延生长的Si0.5Ge0.5合金薄膜的成分有序性。通过分子束外延生长的薄膜合金样品，以及脉冲化学气相沉积生长的样品进行了研究，和半积分反射，表明传统的立方晶胞的两倍，在所有样品中观察到。以绝对单位测量的定量结构因子与建议的结构模型进行了比较，以提取原子结构和组成有序度。的测量结果是一致的双层阶梯流生长模型，其中订购的结果从原子偏析在特定的扭结网站的预测。除了半积分反射，弱积分hkl反射，这是禁止的金刚石结构，也被观察到。这些反射归因于类似于CuAu-I的二级有序结构的存在，具有沿着面内[100]方向的超晶格周期性。
Compositional ordering in Si 0.5 Ge 0.5 alloy films grown epitaxially on Si (001) substrates was investigated using four-circle x-ray-diffraction measurements. Thin-film alloy samples grown by molecular-beam epitaxy, as well as a sample grown by pulsed chemical vapor deposition were studied, and half-integral reflections, indicating a doubling of the conventional cubic unit cell, were observed in all samples. Quantitative structure factors measured in absolute units were compared with proposed structural models to extract the atomic structure and degree of compositional ordering. The measurements are consistent with the predictions of a bilayer step-flow growth model in which ordering results from atomic segregation at specific kink sites. In addition to the half-integral reflections, weak integral hkl reflections, which are forbidden for the diamond structure, were also observed. These reflections are attributed to the presence of a secondary ordered structure similar to CuAu-I, with a superlattice periodicity along the in-plane [100] direction.