Anomalous reactivity of InAs-deposited GaAs surfaces

We examine the surface reactivity of InAs-covered GaAs(100) surfaces as a function of surface InAs coverage using trimethylgallium (TMG) as a probe molecule, which is a typical source material for the epitaxial growth methods of compound semiconductors. We find an anomalous behaviour of the dependence of TMG decomposition rate; the surface decomposition rate is not determined simply by the fraction of the surface covering elements. TMG decomposition rate on the InAs-covered GaAs (100) surface is constant and close to that on the clean GaAs surfaces as far as the two-dimensional growth is maintained, even when the surface is fully covered with InAs. The results are discussed on the basis of the surface structure