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Control of the heteroepitaxal growth on vicinal surfaces

邻近表面异质外延生长的控制

基本信息

批准号：
11555188
负责人：
OSAKA Toshiaki
金额：
$ 4.03万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

In this study, we aimed (i) to prepare a vicinal surface on the Si(111) substrate, (ii) to grow a diamond type of Sn (α-Sn) on the surface, which is the same IV group to Si and is in a large lattice-mismatched relationship with it, and (iii) to control stably its growth morphology.Prior to our experiments, firstly, elastic-strain energy stored at the interface of α-Sn/Si(111) was calculated theoretically using the Keating potential. This calculation gave us the important suggestion that steps on the Si(111) vicinal surface may relax effectively strain energy in the growing film and allow to grow pseudomorphologically α-Sn beyond a critical thickness. On the basis of this result, secondly, we actually grew α-Sn on the 6゜ -inclined vicinal surface, and assessed its process by using reflection high-energy electron diffraction (RHEED) and scanning turneling microscopy (STM).These results are as follows : RHEED patterns showed that terraces on the vicinal substrate used are inclined against the direction normal to the substrate surface and their widths are very narrow. From the STM observation, we gained information of linearity in the step line and nonuniformity in the terrace. Depositing Sn on such vicinal surfaces, we recognized the formation of an adsorption structure having a √3×√3 -R30゜ period. Then, excess Sn forms an α phase, leading to the formation of a facet inclined 19.5゜ form the [11-2] direction of Si(111). Although further growth of Sn causes a phase change from α to β, finally, the whole film becomes α-Sn, presumably stimming from an origin of soft elasticity of Sn.The results show that the utilization of a vicinal surface enables us to control stably the morphology of epitaxicially grown films in the large lattice-mismatched systems.

在这项研究中，我们的目的是（i）在Si（111）衬底上制备邻接表面，（ii）在表面上生长金刚石型的Sn（α-Sn），它与Si同为IV族，并且与Si具有较大的晶格失配关系，以及（iii）稳定地控制其生长形貌。在我们的实验之前，首先，在Si（111）的界面上存储弹性应变能 α-Sn/Si(111) 使用基廷势进行理论计算。该计算为我们提供了重要的建议，即Si(111)邻面上的台阶可以有效地松弛生长薄膜中的应变能，并允许假形生长α-Sn超过临界厚度。其次，在此结果的基础上，我们实际上在6゜倾斜的邻面上生长了α-Sn，并通过使用反射高能电子衍射（RHEED）和扫描车削显微镜（STM）评估了其过程。这些结果如下：RHEED图案表明，所使用的邻位衬底上的台阶相对于衬底表面的法线方向倾斜，并且其宽度非常窄。从STM观察中，我们获得了阶梯线的线性度和平台的不均匀性信息。在这样的邻近表面上沉积Sn，我们认识到形成了具有√3×√3 -R30゜周期的吸附结构。然后，过量的Sn形成α相，导致形成与Si(111)的[11-2]方向倾斜19.5゜的小面。尽管Sn的进一步生长会导致从α到β的相变，但最终整个薄膜变成α-Sn，这可能是由于Sn的软弹性起源所致。结果表明，利用邻接表面使我们能够在大晶格失配系统中稳定地控制外延生长薄膜的形貌。