Effect of strain on surface morphology in highly strained InGaAs films

The early stages of growth of highly strained ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As on GaAs(100) have been investigated as a function of composition. The evolution of the film microstructure as determined by in situ STM and RHEED is from a two-dimensional rippled surface in the beginning stages of growth to a three-dimensional island morphology. A growth mode is proposed whereby strain relaxation is initially achieved through the kinetically limited evolution of surface morphology. In contrast to traditional critical-thickness theories, significant strain relief is accommodated by a coherent island morphology. This study represents a new view for both the growth mode and initial strain relaxation in thin films.