AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS3-TuA

Paper SS3-TuA10
The Effect of As@sub 4@ Flux on the Ga Diffusion on the GaAs(001)-(2x4) Surface

Tuesday, October 26, 1999, 5:00 pm, Room 607

Session: Diffusion on Surfaces
Presenter: D.W. Bullock, University of Arkansas
Authors: D.W. Bullock, University of Arkansas
V.P. LaBella, University of Arkansas
Z. Ding, University of Arkansas
P.M. Thibado, University of Arkansas
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The activation energy for an individual Ga atom to hop across the technologically important GaAs(001) 2x4 reconstructed surface as a function of As@sub 4@ flux was measured. This study was motivated by the ongoing development of short-period III-V semiconductor superlattices for electronic and optoelectronic applications grown by molecular beam epitaxy (MBE). This study was carried out in an ultrahigh vacuum MBE system with an in situ scanning tunneling microscope (STM) to study III-V single cryst al surfaces and interfaces on the atomic scale. The diffusion measurement was achieved by measuring the number density of islands as a function of substrate temperature and As@sub 4@ flux, and comparing it to random walk computer simulations of the grow th process. The Ga atom's relative probability to stick to existing island edges and its relative diffusion anisotropy are estimated. Interestingly, it was discovered that increasing the As@sub 4@ pressure forces the Ga atoms to diffuse more isotropically. This work was funded in part by the National Science Foundation (DMR-9733994) and the Office of Naval Research (N00014-97-1-1058).