2000 Fiscal Year Final Research Report Summary
Thin Film Growth around Misfit Dislocations
| Project/Area Number |
11450005
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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 | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
HIRAYAMA Hiroyuki Interdisciplinary School of Science & Engineering, Tokyo Institute of Technology, Associate Professor, 大学院・総合理工学研究科, 助教授 (60271582)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAYANAGI Kunio Interdisciplinary School of Science & Engineering, Tokyo Institute of Technology, Professor, 大学院・総合理工学研究科, 教授 (80016162)
OHSHIMA Yoshifumi Interdisciplinary School of Science & Engineering, Tokyo Institute of Technology, Assistant, 大学院・総合理工学研究科, 助手 (80272699)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Silicon / Germanium / Molecular Beam Epitaxy / Scanning Tunneling Microscope / Step Morphology / Surface Stress / Misfit Dislocation |
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| Research Abstract |
Si/Ge hetero-structure has been paid much attention in Si-based two-dimensional confinement of electrons and holes, and also in self assembling of quantum dots recently. A key of these applications is the control of the growth mode at the strained hetero-interfaces. However, a detail of the Si layers growth on the Si_<1-x>Ge_x (001 ) surface is still not well investigated. Here, we report our study on the growth of Si layers on Si_<1-x>Ge_x/Si (001) surfaces using STM.
First, we observed the surface morphology of the Si_<1-x>Ge_x (001) layers of various thickness grown on the Si (001) substrates. The surface of the 0.46nm thick Sil-xGex layer include many dimer vacancies in the 2x1 reconstruction. However, the step density was small enough to keep the surface flat as the Si (001) substrate. Increasing the thickness, the dimer vacancies aligned to lines to release the compressive strain on the Si_<1-x>Ge_x (001) surface. The distance between dimer vacancy lines reduced to 8a (a is the su
… More
rface unit cell length) on the Si_<1-x>Ge_x layer of 1.38nm thickness.On the surface with dimer vacancy lines, small terraces stacked to make the surface uneven. SA step tended to be rough while SB step became straight in contrast to the Si (001) 2x1 surface. At the surface of the Sil-xGex layer with the thickness over 2nm, pyramidal 3D islands with (105) facets were observed to nucleate.
In Si deposition, the dimer vacancies disappeared and many small terraces appeared in the initial stage on the Si_<1-x>Ge_x (001) layer of 0.46nm thickness. The terrace size became larger and the surface recovered smoothness in further deposition of Si. On the Si_<1-x>Ge_x (001) layer of 1.38nm thickness, patchy small terraces disappeared and the surface became smoother in the Si deposition. But, the dimer vacancy lines still persisted for the Si coverage up to 1nm, probably due to the segregation of Ge. In the conference, more details of the morphological change on the Si layers grown on the Si_<1-x>Ge_x (001) surface will be presented, and will be discussed from the viewpoints of the accumulation and release of stain and Ge out-diffusion on the growth front. Less
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Research Products
(12 results)
