Structure Analysis of Point-Defect-Aggregates in Semiconductors by Means of Crystallographic Techniques

半导体材料在晶体生长、热处理、电子辐照和离子注入过程中存在点缺陷。众所周知，它们在高温下有相当大的机会聚集在一起。一些聚集体的原子结构仍然不确定，这一事实造成了不必要的混乱。在本研究中，利用透射电子衍射和透射电子显微镜分析了聚集体的原子结构。由于构成共价材料的原子即使在缺陷区也有形成共价键的强烈倾向，因此可以预期聚集体的原子结构具有某种秩序。这就是透射电子衍射和电子显微技术的优势所在，它们是分析嵌入在基体晶体中的具有周期性结构的小颗粒的非常方便的手段。我们的分析结果总结如下。1 .更多。在{113}上的Si缺陷和GeA提出的原子模型表明，间隙的Si原子聚集在{113}上，并在Si晶体内部形成重构结构。该模型具有5-6-7和8元原子环的特征，在{110}投影中没有悬空键。6元环构成了六边形结构的小棒，8元环与{113}表面结构有关。基于能量计算证实，重构结构中每个自间隙原子的能量明显小于孤立间隙原子的估计能量。掺硅砷化镓晶体中的平面缺陷在掺硅砷化镓晶体中观察到小的三角形析出物。透射电镜研究表明，在GaAs晶体中，硅的两个{111}晶面插入在两个{111}晶面之间。此外，基于高分辨率电子显微镜图像的精确分析，我们提出了硅中氢诱导血小板的新原子模型。综上所述，电子衍射和显微等晶体学技术在分析半导体材料中点缺陷聚集体的原子结构方面是非常有用的。少

Point defects in a semiconducting material are introduced during crystal growth, heat treatment, electron irradiation and ion-implantation. It is well known that they gave a considerable chance to aggregate at elevated temperatures. Atomic structures of several aggregates have remained uncertain, and this fact has caused unnecessary confusion. In the present research, atomic structures of the aggregates have been analyzed by means of transmission electron diffraction and transmission electron microscopy. Since the atoms which constitute a covalent material have a strong tendency to form covalent bonds even in a defect region, it is expected that the atomic structure of aggregates has a kind of order. This is the reason of the advantage of transmission electron diffraction and electron microscopic techniques, which are very convenient means to analyze small particles of a periodic structure which are embedded in the matrix crystal. The results of our analysis are summarized as follows.1 … More . Defect on {113} in Si and GeA proposed atomic model shows that interstitial Si atoms aggregate on {113} and form a reconstructed structure in the interior of a Si crystal. The model is characterized by 5-6-7-and 8-membered atomic rings and has no dangling bond in the {110} projection. The 6-membered rings constitute tiny rods of the hexagonal structure, and the 8-membered rings are related to the {113} surface structure. It has been confirmed based on an energy calculation that the energy per self interstitial atom in the reconstructed structure is distinctively smaller than that estimated for an isolated interstitial atom.2. Planar defects in a Si-doped GaAs crystalSmall precipitates of triangular shape are observed in a Si-doped GaAs crystal. Transmission electron microscopic study has indicated that the two {111} crystallographic net planes of Si are inserted between the two existing {111} net planes in a GaAs crystal.Furthermore, we have proposed a new atomic model for a hydrogen-induced platelet in Si based on the precise analysis of high-resolution electron microscopic images.In conclusion, the crystallographic techniques such as electron diffraction and microscopy are very useful in analyzing atomic structures of point-defect-aggregates in semiconducting materials. Less