Accession Number:

ADA237504

Title:

Electron Tunneling Microscopy

Descriptive Note:

Final rept. 1 Dec 85-31 Mar 91,

Corporate Author:

CALIFORNIA INST OF TECH PASADENA

Personal Author(s):

Report Date:

1991-06-13

Pagination or Media Count:

12.0

Abstract:

The rapid development of the Scanning Tunneling Microscope STM and its derivatives in the past five years has created new techniques not only for examining surfaces and surface processes, but also for surface modification, lithography and performing surface chemistry and spectroscopy at microscopic levels never before attainable. Understanding the mechanisms involved in these processes will enable researchers to utilize fully the tremendous capabilities potentially available with this technology. STM is based on the phenomenon of quantum mechanical tunneling. A metal tip is brought within a few angstroms of a conducting sample by means of a 3-dimensional piezoelectric ceramic positioner. A tunneling current whose magnitude depends exponentially on the tip-sample separation can be established and maintained by means of a feedback circuit to the positioner. By rastering the tip over the surface x and y and monitoring the feedback to the z position, a topographic image of the surface can be formed. A current image can also be obtained by rastering the tip over the surface at a high frequency so that a constant average height over the surface is maintained. The image contrast is produced by monitoring the fluctuation in current. The exponential dependence of the tunneling current upon the separation of the tip from the surface provides the exquisite resolution of the STM. Author

Subject Categories:

  • Particle Accelerators

Distribution Statement:

APPROVED FOR PUBLIC RELEASE