AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Wednesday Sessions
       Session NS+NANO6+MC-WeM

Paper NS+NANO6+MC-WeM5
Low Temperature Scanning Force Microscopy of the Si(111) 7x7 Surface and Site-specific Measurements of Tip-Sample Interaction Forces

Wednesday, October 4, 2000, 9:40 am, Room 302

Session: Nanomechanical and Interface Measurements
Presenter: M.A. Lantz, University of Basel, Switzerland
Authors: M.A. Lantz, University of Basel, Switzerland
H.J. Hug, University of Basel, Switzerland
S. Martin, University of Basel, Switzerland
A. Abdurixit, University of Basel, Switzerland
A. Baratoff, University of Basel, Switzerland
R. Hoffmann, University of Basel, Switzerland
P. Kappenberger, University of Basel, Switzerland
P.J.A. van Schendel, University of Basel, Switzerland
Ch. Gerber, IBM Research Division, Zuerich Research Laboratory
H.-J. Guentherodt, University of Basel, Switzerland
Correspondent: Click to Email
A low temperature scanning force microscope (SFM) operating in a dynamic mode in ultra high vacuum was used to study the Si(111)7x7 surface at 7.2K. Not only the twelve adatoms but also the six rest atoms of the unit cell are clearly resolved for the first time with SFM. In addition, the first measurements of the short-range chemical bonding forces above specific atomic sites are presented. The data is in good agreement with first-principles computations and indicates that the nearest atoms in the tip and sample relax significantly when the tip apex is within a few Å of the surface.@footnote 1@ New experiments with non-reactive tips reveal atomically resolved images with surprisingly different contrast from those obtained with a reactive tip. Careful analysis of frequency and damping versus distance curves clearly shows the obtained contrast does not result from the formation of a covalent bond, however atomic resolution is still obtained. This strongly suggests that true atomic resolution can be obtained with a new type of tip-sample interaction.The physical nature of this interaction mechanism will be discussed and compared to theoretical models.@FootnoteText@@footnote 1@Lantz et al., Phys. Rev. Lett 84, 2642 (2000).