Scanning tunneling microscope
AssigneeInternational Business Machines Corporation
InventorsGerd Binnig, Heinrich Rohrer
Life of this patent
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Abstract
The vacuum tunnel effect is utilized to form a scanning tunneling microscope. In an ultra-high vacuum at cryogenic temperature, a fine tip is raster scanned across the surface of a conducting sample at a distance of a few Angstroms. The vertical separation between the tip and sample surface is automatically controlled so as to maintain constant a measured variable which is proportional to the tunnel resistance, such as tunneling current. The position of the tip with respect to the surface is controlled preferably by piezo electric drive means acting in three coordinate directions. The spatial coordinates of the scanning tip are graphically displayed. This is conveniently done by displaying the drive currents or voltages of piezo electric drives.
Claims12
Apparatus for investigating surface structures utilizing the vacuum tunnel effect, comprising:
- an ultra-high vacuum chamber which can be cooled down to a temperature close to absolute zero;
- a fine conducting tip in said chamber;
- means for positioning a conductive sample surface in said chamber sufficiently close to said conducting tip that tunnelling current flows between said tip and the sample surface;
- means for scanning said tip across the sample surface at a tunneling distance while tunnelling current flows between said tip and the sample surface;
- means for measuring a tunnel effect variable between said tip and the sample surface while said tip is scanned across the surface;
- means for automatically controlling the separation distance between said tip and the sample surface in response to the measured tunnel effect variable such that the measured tunnel effect variable remains substantially constant during scanning;
- and
- means for graphically displaying the spatial coordinates of said scanning tip to produce a topological map of said surface.
Dependencies are inferred from the claim text.