1996 Fiscal Year Final Research Report Summary
Elucidation and Control of Surface Electronic and Atomic Processes by the Tip
| Project/Area Number |
06452044
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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 |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TSUKADA Masaru The Universiry of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (90011650)
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| Co-Investigator(Kenkyū-buntansha) |
TAMURA Ryo The Universiry of Tokyo, Graduate School of Science, Research Associate, 大学院・理学系研究科, 助手 (20282717)
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| Project Period (FY) |
1994 – 1996
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| Keywords | scanning tuwnneling microscopy / local density functional approach / ricesion-transfer matrix method / atom control / atom extraction / field evaporation / tunnel current / microscopic contact |
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| Research Abstract |
Various phenomena are induced by the nano-scale gap between the tip and the sample surface in the scanning probe microscopy. Among them the elementaly processes of electrons and atoms are most important both for the fundamental science and for the basis of thechnological applications. The purpose of this projet is to develop a theoretical method to describe and predics these processes and clarify their fundamental aspects. For that purpose the first・principles recursiontransfer matrix method is developped which is an extension of the Density Functional Theory for non-equilibrium open systems. In this method wavefunctions are solved in a scattering wave forms and the tunneling tails are very precisely determined. With the method quntitative analyzes of STM,tip induced chemical processes, atom transfer between the tip and over the surface can be studied from the first・principles.
With this method the following problems are studied. The first is the microscopic contact between the two surfaces. A sharp onset of the electronic inceraction of sufaces is found and the details of the potential distribution are studied as well as the concept of the local workiunction.
The mechanism of atom extraction by the tip of STM is clarified as follows. When the tip is negatively biased, the electron cloud is pushed cut in front of the tip apex. Then it is accumlated in the interstitial region between the tip apex atom and the surface atom confronted to it. With the further increase of the negative tip bias, the electron cloud forms a bridge structure with the surface, then a very strong force is acted on the suriace atom. The situationis quite dependent on the tip height and the tip surface materials.
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