Evidence from the surface morphology for nonlinear growth of epitaxial GaAs films

The mesoscale morphology of homoepitaxial GaAs surfaces is explained with a n anisotropic and nonlinear Kardar-Parisi-Zhang (KPZ) model in which adatom s are incorporated into the film from a metastable surface layer. Evaporati on-condensation between the film and the metastable layer is proposed as th e microscopic physical origin of the KPZ description, as well as of the exc ess noise observed in the power spectral density. The parabolic mounds obse rved experimentally in films grown on rough substrates are in good agreemen t with the surface shape expected from the solution of the KPZ equation in the large amplitude limit.