1 April 1990 Picosecond surface-restricted grating studies of n-GaAs (100) surfaces: direct optical detection of surface states
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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.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
L. A. Gomez-Jahn, J. J. Kasinski, R. J. Dwayne Miller, "Picosecond surface-restricted grating studies of n-GaAs (100) surfaces: direct optical detection of surface states", Proc. SPIE 1209, Picosecond and Femtosecond Spectroscopy from Laboratory to Real World, (1 April 1990); doi: 10.1117/12.17894; https://doi.org/10.1117/12.17894
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