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Proceedings Paper

Picosecond surface-restricted grating studies of n-GaAs (100) surfaces: direct optical detection of surface states
Author(s): L. A. Gomez-Jahn; J. J. Kasinski; R. J. Dwayne Miller
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Paper Abstract

The surface restricted transient grating technique has been found to be sensitive to the Fermi levelpinning surface states at the atomic interface of the native oxide layer of (100) GaAs. The sensitivity to these states is better than io of a monolayer. The high sensitivity arises from a surface enhancement effect that is attributedto the delocalized two dimensional character of the electronic state at the surface. The surface enhancement is eliminatedby photoinduced removal of the oxide layer and hole transfer to Se2 ions adsorbed to the surface. These resultssupport the assignment of the signal to electronic factors associated with surface state species. The coulombic bindingenergy of the minority hole carrier, into a 2-d hydrogenic state centered around these negatively charged surfacestates, is .16 eV. This coulombic trapping must be the first step in the surface state trappingprocess and rationalizes the picosecond surface state trapping dynamics observed at GaAs surfaces. In addition, the in-situ studies of hole transfer to Se2 at liquid junctions found the hole transfer time to be less than 30 psec. Relative to the thermalization time scale of space charge accelerated hole carriers, this result demonstrates that hot hole transfer contributes at least a fewpercent. to this surface reaction mechanism.

Paper Details

Date Published: 1 April 1990
PDF: 12 pages
Proc. SPIE 1209, Picosecond and Femtosecond Spectroscopy from Laboratory to Real World, (1 April 1990); doi: 10.1117/12.17894
Show Author Affiliations
L. A. Gomez-Jahn, Univ. of Rochester (United States)
J. J. Kasinski, Univ. of Rochester (United States)
R. J. Dwayne Miller, Univ. of Rochester (Canada)

Published in SPIE Proceedings Vol. 1209:
Picosecond and Femtosecond Spectroscopy from Laboratory to Real World
Keith A. Nelson, Editor(s)

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