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Metastable Structural Surface Excitations and Concerted Adatom Motions: a STM Study of Atomic Motions Within a Semiconductor Surface

Published online by Cambridge University Press:  15 February 2011

Jene Golovchenko
Affiliation:
Department of Physics and Division of Applied Sciences, Harvard University, Cambridge, MA 02138
Ing-Shouh Hwang
Affiliation:
Department of Physics and Division of Applied Sciences, Harvard University, Cambridge, MA 02138
Eric Ganz
Affiliation:
Department of Physics and Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis, MN 55455
Silva K. Theiss
Affiliation:
Department of Physics and Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis, MN 55455
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Abstract

Knowledge about atomic scale motions is essential to the understanding of dynamical phenomena on surfaces, such as diffusion, phase transitions, and epitaxial growth. We demonstrate that the addition of a very small number of Pb atoms to a Ge(111) surface reduces the energy barrier for activated processes, thus allowing one to observe concerted atomic motions and metastable structures on this surface near room temperature using a tunneling microscope. The activation energy for surface diffusion of isolated substitutional Pb atoms in Ge(111)-c(2×8) was measured by observing individual atomic interchanges from 24°C to 79°C. We also observed the formaticn and annihilation of metastable structural surface excitations, which are associated with large numbers of germanium surface atoms in one row of the c(2×8) reconstruction shifting along that row like beads on an abacus. The effect provides a new mechanism for atomic transport on semiconductor surfaces and can explain a number of other observed phenomena associated with Ge(111) surfaces, including the surface diffusion of Pb atoms.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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