Continuous and discontinuous metal-organic vapor phase epitaxy of coherent self-assembled islands: effects on size homogeneity

摘要

The size-homogeneity of coherent three-dimensional islands of InPk on GaAs forming during self-assembling or Stranski-Krastanow growth is studied (i) for continuous and (ii) for discontinuous growth of the strained layer. A high homogeneity in size is achieved only if the material for island formation is deposited t once. Deposition of the same amount in portions amplifies small differences in size, thereby losing the size homogeneity. An explanation is given by assuming that during continuous growth most of the material reaches the islands by surface diffusion from the reservoir wetting layer. For this case the strain-induced diffusion barrier around coherent islands is size-regulating. For discontinuous growth the direct diffusive flux of material from the vapor phase towards the islands, which represent the local minim of the chemical potential at the surface, becomes more important. For this case no size-regulation mechanism exists, in contrast, the material diffuses preferentially towards the already larger islands.