2000 Fiscal Year Final Research Report Summary
Control of the heteroepitaxal growth on vicinal surfaces
| Project/Area Number |
11555188
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | Waseda University |
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Principal Investigator |
OSAKA Toshiaki Waseda University, School of Science and Engineering, Professor, 理工学部, 教授 (50112991)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Si(111) / vicinal surface / controlling growth morphology / critical film thickness / strain relaxation / surface step |
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| Research Abstract |
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.
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