Scanning tunneling microscopy and spectroscopy: Theory, techniques, and applications. Edited byD. A. Bonnell, VCH Publishers, Inc., New York 1993, XIV, 436 pp., hardcover, DM 196, ISBN 0-89-573-768-X (original) (raw)

Scanning tunneling microscopy and spectroscopy: theory, techniques, and applications

We report room temperature scanning tunneling microscopy and spectroscopy study of bilayer graphene prepared by mechanical exfoliation on SiO2/Si surface and electrically contacted with gold pads using a mechanical mask. The bulk conductivity shows contribution from regions of varying electron density indicating significant charge inhomogeneity. Large scale topographic images show ripple like structures with a roughness of ∼1nm while the small scale atomic resolution images show graphite-like triangular lattice. Local dI/dV-V tunnel spectra have an asymmetric V-shape with the minima location showing significant spatial variation indicating inhomogeneity in electron density of order 10 11 cm−2. The minima in spectra at a fixed location also shifts linearly with the gate voltage with a slope consistent with the field induced carrier density.

Theory of Scanning Tunneling Microscopy and Spectroscopy

1990

A method for simulating scanning tunneling microscopy (STM) and spectroscopy (STS) is proposed, 0 which is effective at realistic tip-to-surface distances of 5-10 A, and its application is reported for Si(100) reconstructed surfaces. The vacuum tails of wave functions cannot be accurately described either by linear combination of atomic orbitals or by pure plane-wave expansion. An attempt is made to effectively describe the tail parts by combining this method with realistic calculations of the sample surface electronic states. The method is applied to Si(100) reconstructed surfaces and the features of the STM images and STS spectra of 2X1 dimer structures are clarified. This method confirms that the experimental c(4X2) image of STM is actually obtained from the c (4X2) structure and reveals how the buckling of dimers is rejected on the STM image.

Tunneling spectroscopy: surface geometry and interface potential effects

Surface Science, 1990

The dependence of the oscillations observed in scanning tunneling microscopy of the tunneling conductance with applied bias vohage on the tip's curvature and the interface potential has been studied. A triaf and error analysis of the distance-voltage and conductance-voltage characteristics is used to determine both the radius of the tip and the parameters fixing the interface potential. The effect of asperities in the tip and sample on the oscillations and the dependence of the oscillations on the sign of the applied bias are also discussed.

Introduction to Scanning Tunneling Microscopy

1993

In a 1959 speech entitled There's Plenty of Room at the Bottom [1], Richard Feynman invited scientists to a new field of research: to see individual atoms distinctly, and to arrange the atoms the way we want. Feynman envisioned that, by achieving those goals, one could synthesize any chemical substance that the chemist writes down, resolve many central and fundamental problems in biology at the molecular level, and dramatically increase the density of information storage. Some 20 years later, those goals began to be achieved through the invention and application of the scanning tunneling microscope (STM) [2, 3] and the atomic force microscope (AFM) . The inventors of STM, two physicists at IBM Research Division, Gerd Binnig and Heinrich Rohrer, shared the 1986 Nobel Prize in physics .

Atomic theory of scanning tunneling microscopy

Physical Review B - PHYS REV B, 1989

We present a quantitative analysis of the modifications of the scanning-tunneling-microscopy images due to the local perturbations of the electronic states induced by the tip in close proximity to the sample surface. Using an empirical tight-binding method, we have calculated the electronic states of a prototype tip-sample system consisting of a single-atom tip and the graphite surface, as a function of the tip-sample distance. We find that as the tip approaches the sample, their states start to interact and become laterally confined in the vicinity of the tip at small tip-sample separation. These states influence the tunneling phenomenon by connecting the tip and sample surface electronically. The effect of the tip-induced localized states is discussed, and the expression for the tunneling current is reformulated by incorporating the tip-induced states. Calculations using this expression show that the corrugation amplitude obtained from scanning tunneling microscopy is enhanced and...

Tunneling tips imaged by scanning tunneling microscopy

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1990

Electrochemically etched tips commonly used for scanning tunneling microscopy (STM) have been investigated by STM itself. By appropriate positioning, the topography of the apex of the tips could be investigated, leading to a typical value for the tip radius of 300 nm. Different techniques have been attempted to untangle the convoluted STM image. By rotating one tip relative to the other, or by exchanging one tip and leaving the other in place, some distinct features can be attributed to the one or the other tip. Furthermore, the profile of the tip could be investigated by scanning over the edge of a cleaved crystal. Beside the fundamental interest in the tip structure itself, this configuration offers the unique feature of unambiguous relocation of the scanned area when the tip investigated in that experiment has been removed and reinstalled to the microscope.

In situ scanning tunneling microscopy

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1990

The successful expansion which the scanning tunneling microscopy (STM) has had is dependent on its ability to examine surfaces on a sub-nanometric scale and on providing in situ (i.e. in the presence of bulk electrolyte) sample examination. In addition to the ability to study metals and semiconductors in vacua, the application of the technique to surfaces in contact with an electrolytic solution has prompted increased interest amongst electrochemists. We discuss herein the technique, with particular reference to advances in electrochemical applications. A new scanning tunneliig microscope for operation in electrolytic environments is described. Atomic force microscopy, scanning electrochemical microscopy and scanning ion-conducting microscopy are compared with the STM.

Scanning tunneling spectroscopy at the single atom scale

This thesis reports measurements at the single atom scale by using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Different sample systems where analyzed with normal conducting and superconducting tips.