Theory and Application for the Scanning Tunneling Microscope
TL;DR: In this article, a theory for vacuum tunneling between a real solid surface and a model probe with a locally spherical tip is presented, applicable to the recently developed "scanning tunneling microscope."
Abstract: A theory is presented for vacuum tunneling between a real solid surface and a model probe with a locally spherical tip, applicable to the recently developed "scanning tunneling microscope." Calculations for 2\ifmmode\times\else\texttimes\fi{}1 and 3\ifmmode\times\else\texttimes\fi{}1 reconstructions of Au(110) are in excellent agreement with recent experimental results, if an effective radius of curvature of 9 \AA{} is assumed for the tip.
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TL;DR: In this paper, a metal tip is scanned along the surface while ad justing its height to maintain constant vacuum tunneling current, and a contour map of the surface is generated.
Abstract: The recent development of the “scanning tunneling microscope” (STM) by Binnig et al. [8.1–5] has made possible the direct real-space imaging of surface topography. In this technique, a metal tip is scanned along the surface while ad justing its height to maintain constant vacuum tunneling current. The result is essentially a contour map of the surface. This contribution reviews the the ory [8.6–8] of STM, with illustrative examples. Because the microscopic structure of the tip is unknown, the tip wave functions are modeled as s-wave functions in the present approach [8.6, 7]. This approximation works best for small effective tip size. The tunneling current is found to be proportional to the surface local density of states (at the Fermi level), evaluated at the position of the tip. The effective resolution is roughly [2A(R+d)]1/2, where R is the effective tip radius and d is the gap distance. When applied to the 2x1 and 3x1 reconstructions of the Au(l10) surface, the theory gives excellent agreement with experiment [8.4] if a 9 A tip radius is assumed. For dealing with more complex or aperiodic surfaces, a crude but convenient calculational technique based on atom charge superposition is introduced; it reproduces the Au(l10) results reasonably well. This method is used to test the structure-sensitivity of STM. The Au(l10) image is found to be rather insensitive to the position of atoms beyond the first atomic layer.
3,192 citations
TL;DR: In this paper, the authors review the fundamentals, applications and future tendencies of dynamic atomic force microscopy (AFM) methods and present a detailed quantitative comparison between theoretical simulations and experiment.
1,908 citations
Book•
20 May 1993
TL;DR: In this paper, the authors present an overview of the imaging mechanism for tunneling, including tip-sample interactions and tip treatment, and a detailed description of the tunneling matrix elements.
Abstract: 1: Overview. Part I: Imaging Mechanism. 2: Atom-scale tunneling. 3: Tunneling matrix elements. 4: Wavefunctions at surfaces. 5: Imaging crystalline surfacces. 6: Imaging atomic states. 7: Atomic forces and tunneling. 8: Tip-sample interactions. Part II: Instrumentation. 9: Piezoelectric scanner. 10: Vibration isolation. 11: Electronics and control. 12: Coarse positioner and STM design. 13: Tip treatment. 14: Scanning tunneling spectroscopy. 15: Atomic force microscopy. 16: Illustrative examples. Appendices. References. Index
1,413 citations
Cites methods from "Theory and Application for the Scan..."
...According to the Tersoff-Hamann model of STM imaging [16, 17] (see Chapter 6), a topographic STM image is the contour of equal Fermi-level local density of states of the sample, measured at the center-of-curvature of the tip r0, ρ(EF , r0)....
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01 Jan 1985
TL;DR: A theory for tunneling between a real surface and a model probe tip, applicable to the recently developed "scanning tunneling microscope" is presented and it is concluded that for the AuOlO measurements the experimental "image" is relatively insensitive to the positions of atoms beyond the first atomic layer.
Abstract: The recent development of the “scanning tunneling microscope” (STM) by Binnig et al. [8.1–5] has made possible the direct real-space imaging of surface topography. In this technique, a metal tip is scanned along the surface while ad justing its height to maintain constant vacuum tunneling current. The result is essentially a contour map of the surface. This contribution reviews the the ory [8.6–8] of STM, with illustrative examples. Because the microscopic structure of the tip is unknown, the tip wave functions are modeled as s-wave functions in the present approach [8.6, 7]. This approximation works best for small effective tip size. The tunneling current is found to be proportional to the surface local density of states (at the Fermi level), evaluated at the position of the tip. The effective resolution is roughly [2A(R+d)]1/2, where R is the effective tip radius and d is the gap distance. When applied to the 2x1 and 3x1 reconstructions of the Au(l10) surface, the theory gives excellent agreement with experiment [8.4] if a 9 A tip radius is assumed. For dealing with more complex or aperiodic surfaces, a crude but convenient calculational technique based on atom charge superposition is introduced; it reproduces the Au(l10) results reasonably well. This method is used to test the structure-sensitivity of STM. The Au(l10) image is found to be rather insensitive to the position of atoms beyond the first atomic layer.
1,065 citations