1995 Fiscal Year Final Research Report Summary
Construction of an experimental apparatus for atom transfer between nano-regions
| Project/Area Number |
05555007
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
表面界面物性
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| Research Institution | Japan Advanced Institute of Science and Technology, Hokuriku (1994-1995)
Tokyo Institute of Technology (1993) |
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Principal Investigator |
TOMITORI Masahiko Associate Professor Japan Advanced Institute of Science and Technology, Hokuriku School of Materials Science, 材料科学研究科, 助教授 (10188790)
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| Project Period (FY) |
1993 – 1995
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| Keywords | atom transfer / scanning tunneling microscopy / scanning tunneling spectroscopy / field emission microscopy / inertia piezomotor / build-up / tungsten / silicon |
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| Research Abstract |
Recently, atom transfer in STM has attracted much interest. However, the mechanism of atom transfer in STM has not been revealed, because the experimental conditions are not always constant ; the induced high field and passing current in the proximity region between the tip and the sample are affected by the atomic structure of the tip apex. Then we have constructed a new UHV-STM/FEM with a tolerance of applying a high voltage of 10kV and increasing the tip temperature to 1500ﾟC in the STM head. The design makes possible the cleaning and build-up of the STM tip utilizing thermal field evaporation. The tip can be positioned on the surface using a 3-dimensional mechanical stage, which driven by inertia-piezomotor screws with a 30nm step. The STM and FEM operation modes can be easily switched ; the tip can be aligned to a tapered small hole of the STM sample holder, adjacent to the sample, and then the pattern of field emitted electrons from the tip can be projected on the screen behind the sample. Thus the tip apex can be evaluated before and after the experiments of atom transfer.
We have studied Si (111)7x7 by STM/STS using a [111]-oriented W tip, which was built-up by heating it while applying a positive high voltage. STS measurements sweeping from-3 to 3 V resulted in unstable tunneling spectra. Immediately after the STS measurements, FEM images showed that the apex changed drastically to be darker at the center. This result indicates that the Si atoms were transferred to the tip apex by the sweeping voltages and the adsorption of Si on the tip apex increased the workfunction of the apex. This is the evidence of Si atom transfer in the STS measurements.
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