1999 Fiscal Year Final Research Report Summary
Mesoscopic Pattern Formation in Crystal Surfaces
| Project/Area Number |
09640392
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Nagoya University |
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Principal Investigator |
UWAHA Makio Nagoya University, Department of Physics, Associate Professor, 大学院・理学研究科, 助教授 (30183213)
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| Project Period (FY) |
1997 – 1999
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| Keywords | step / morphological instability / crystal growth / bunching of steps / wandering of steps / nonlinear evolution equation / silicon / pattern formation |
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| Research Abstract |
We studied motion of atomic steps in the surface diffusion filed systematically and obtained the following results :
1. Symmetry of the system determines whether destabilized steps show chaotic behavior or stable structure. For the step wandering instability induced by the drift of adsorbed atoms, we showed that it is possible to change the chaotic motion to a periodic pattern by controlling the direction of the drift. We also clarified effect of the anisotropy in stiffness and kinetic coefficient.
2. In the bunching instability with the drift we found theoretically that the bunch grows in a power law with time with exponent 1/2 agreement with experiments of Si. If the drift is weak, this exponent becomes small and the bunch size saturates as we have predicted.
3. We derived nonlinear evolution equation for a two-dimensional continuum model and studied pattern formation of a vicinal surface. We found that two domains of ridge tilted from the symmetry axis develop if the wandering and the bunching occur simultaneously.
4. With the linear stability analysis and Monte Carlo simulation, we studied, for various cases, the wandering and the bunching of steps induced by the drift. We allow absorbed atoms to pass through the steps. With this step permeability we can dissolve the contradiction between a recent experiment of step wandering in Si(111) and our theoretical prediction.
5. We studied decay process of a three-dimensional island on a large facet using a model on isotropic concentric steps. With a simple heuristic argument we derived a growth law of a facet size that appears on the top of the island. We analyzed an STM observation of the decay of a nanometer size Si island. Surprising agreement with the theory shows that the continuum theory with macroscopic step parameters are valid down to such a small size.
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