The morphology of As terminated Si(111) from desorption kinetics.

Isothermal desorption measurements of film/substrate systems yield rate parameters characteristic of the thermodynamical driving forces which determine the film morphology. We show from the activation energy for desorption for As on Si(111) that it is energetically favorable to form a uniform layer rather than clustering (for coverages up to ~1 monolayer). This is supported by the fact that the desorption process follows a second-order kinetic law. The preexponential factor for desorption is consistent with a restricted surface mobility of the adatoms. These results bear on issues associated with the growth of GaAs on Si.