Gerd K. Binnig

Single‐tube three‐dimensional scanner for scanning tunneling microscopy

We report a new type of three‐dimensional mechanical scanner fabricated from a single piezoelectric tube. It has a typical response of 5 nm/V in each orthogonal direction and mechanical resonances at 8 kHz (bending perpendicular to the tube axis) and 40 kHz (motion parallel to the tube axis). When used in a scanning tunneling microscope it is the higher frequency mode which is most critical since it corresponds to motion perpendicular to the sample surface. We show an image of the atomic surface of graphite taken in air using a tube scanner incorporated into a scanning tunneling microscope. The tube scanner allows the development of smaller, simpler, and faster scanning tunneling microscopes.

Ultrasmall scanning tunneling microscope for use in a liquid‐helium storage Dewar

We describe a scanning tunneling microscope which is extremely compact and rigid. Neither springs nor stacks of metal plates and rubber are necessary for vibration isolation. It can resolve the atomic structure of graphite at room and liquid‐helium temperatures. Its small size permits it to be dipped into a standard liquid‐helium storage Dewar.

Atomic point-contact imaging

In tunneling microscopy a potential barrier separates a pointed tip from the sample to be investigated. In this letter we show that atomic resolution can be achieved in special cases where the gap spacing has been reduced to the point where the potential barrier may have completely collapsed. In this example the tip may be said to be touching the sample. The forces between the tip and sample are then strongly repulsive and the possibility exists for studying tribology on an atomic scale.

Detection of phonons with a scanning tunneling microscope

A well defined spectrum of peaks in d2I/dV2 vs V has been obtained with a tunneling microscope immersed in liquid helium. The positions of the peaks correspond closely to the energies of the phonons of the graphite sample and the tungsten tip. We propose that electrons coupling to the bulk phonons near the tip to sample gap cause the observed increases in the tunneling conductance. Spectroscopic imaging at a phonon energy shows spatial variations of the vibrational spectra on an atomic scale.

Anomalous distance dependence in scanning tunneling microscopy

In this work it is found experimentally that the appearance of surfaces in scanning tunneling microscope (STM) images can change drastically as the distance between the STM tip and sample is varied. Defects are found on gold‐sputtered graphite samples which appear as protrusions in charge density when the spacing exceeds a critical value. At smaller distances the protrusions are not evident in the images. It is possible to model these defects as gold atoms which lie just below the surface layer. We discuss possible mechanisms that give rise to the distance dependence.

The Millipede – A Nanotechnology-Based AFM Data-Storage System

The millipede concept presented in this chapter is a new approach to storing data at high speed and ultrahigh density. The interesting part is that millipede stores digital information in a completely different way from magnetic hard disks, optical disks, and transistor-based memory chips. The ultimate locality is provided by a tip, and high data rates are a result of massive parallel operation of such tips. As storage medium, polymer films are being considered, although the use of other media, in particular magnetic materials, has not been ruled out. The current effort is focused on demonstrating the millipede concept with areal densities higher than 1 Tb/inch2 and parallel operation of very large two-dimensional (2-D) (up to 64 × 64) atomic force microscopy (AFM) cantilever arrays with integrated tips and write/read/erase functionality. The fabrication and integration of such a large number of mechanical devices (cantilever beams) will lead to what we envision as the very large-scale integration (VLSI) age of micro- and nanomechanics.