A scanning tunneling microscopy tip with a stable atomic structure |
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Authors: | Email author" target="_blank">Yeong-Cheol?KimEmail author David?N?Seidman |
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Affiliation: | (1) Department of Materials Engineering, Korea University of Technology and Education, San 37 Gajeon-ri, Byeongcheon-myeon, 330-708 Choenan, Korea;(2) Department of Materials Science and Engineering R. R. McCormick School of Engineering and Applied Science, Northwestern University, 2220 Campus Drive, 60208-3108 Evanston, IL, USA |
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Abstract: | A single stable adatom on a {110}-type plane of a tungsten tip is created via field-evaporation in a field-ion microscope
(FIM) operating at room temperature. This single adatom has sufficient surface mobility at room temperature and migrates,
in one-dimension, along a <111>-type direction toward an edge of a {110}-type plane, due to the existence of an electric field
gradient. The plane edge has a higher local electric field than its center, since it has a higher local geometric curvature.
This result implies that the stable position of a single adatom during a scan of a scanning tunneling microscope (STM) tip
on a surface is at the edge and not at the center of a {110}-type plane at room temperature. Therefore, the electron wave
function of a tip is not symmetric and this fact should be taken into account in a careful analysis of STM images. Also a
tip with a dislocation emerging at a {110}-type plane is suggested as an improved STM tip configuration, as the step at the
surface, created by the intersection of the dislocation with it, is a perpetual source of single adatoms. |
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Keywords: | field-ion microscopy scanning tunneling microscopy tungsten tip adatom dislocation |
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