Surface flattening by annealing after molecular beam epitaxy growth revealed by in-situ secondary electron microscopy

The consecutive evolution of the configurations of islands, steps and terraces on a GaAs(001) surface during annealing after growth was studied by in-situ observation using a secondary electron microscope. Three unexpected processes were revealed: some large two-dimensional islands grow, although most small ones shrink, step distances becomes more uniform rather than step bunching occurring, and multilayer high islands shrink and disappear. The latter two processes play an important role in surface flattening. The growth of islands is explained by thermodynamic equilibrium.