J. Phys. IV France 09 (1999) Pr8-3-Pr8-14
Site-specific chemistry of gallium arsenide metalorganic chemical vapor depositionQ. Fu, L. Li, M.J. Begarney, B.-K. Han, D.C. Law and R.F. Hicks
Chemical Engineering Department, University of California, Los Angeles, CA 90095-1592, U.S.A.
Herein, we summarize our studies of the surface chemistry of gallium arsenide as it pertains to the metalorganic chernical-vapor deposition of compound semiconductors. It has been found by scanning tunneling microscopy and vibrational spectroscopy that the adsorption of reactant molecules on reconstructed GaAs (001) surfaces is "site-specific." Trimethylgallium dissociatively adsorbs only on arsenic sites, whereas arsine dissociatively adsorbs only on gallium sites. The decomposition of one precursor molecule (Ga(CH3)3 or AsH3 creates the site for the decomposition of the other molecule (AsH3 or Ga(CH3)3, respectively). In this fashion, the crystal grows one atomic layer at a time. Studies of carbon doping with carbon tetrachloride have shown that adsorbed chlorine attacks the exposed gallium and generates volatile GaClx species. The sitespecific nature of this reaction leads to a dramatic change in the film morphology, with the formation of 30 nm etch pits randomly distributed over the surface.
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