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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.

在本研究中，我们的目标是（i）在Si（111）衬底上制备邻位表面，（ii）在表面上生长与Si具有相同IV族且与Si具有大晶格失配关系的金刚石型Sn（α-Sn），（iii）稳定地控制其生长形貌。利用Keating势理论计算了α-Sn/Si（111）界面的弹性应变能。计算结果表明，Si（111）邻面台阶能有效地弛豫生长膜中的应变能，使α-Sn赝象生长超过临界厚度。在此基础上，我们在6 °倾斜的邻位衬底上生长了α-Sn，并利用反射式高能电子衍射（RHEED）和扫描旋转显微镜（STM）对其生长过程进行了评价，结果表明：RHEED图显示，所用邻位衬底上的台阶与衬底表面的法线方向相反，且宽度很窄。从STM观察中，我们得到了台阶线的线性和平台的非均匀性的信息。将Sn沉积在这种邻位表面上，我们确认形成了具有103 × 103-R30 π周期的吸附结构。然后，过量的Sn形成α相，导致形成从Si（111）的[11-2]方向倾斜19.5 °的小面。虽然Sn的进一步生长会引起α到β的相变，但最终整个薄膜变成α-Sn，这可能是由于Sn的软弹性引起的.结果表明，在大晶格失配系统中，利用邻位面可以稳定地控制外延生长薄膜的形貌.