Characterization of compositional oscillations in InGaAs films induced by MBE cell configuration and substrate rotation

We examine compositional non-uniformities in InGaAs films grown on InP substrates by molecular beam epitaxy (MBE). Transmission electron microscope (TEM) images of samples cut near the edge of the wafer show periodic bands of contrast typical of a superlattice. Flux variations across the wafer lead to mole fraction oscillations that are dependent on the growth rate and substrate rotation speed. Without careful analysis, this film morphology could be mischaracterized as spontaneous ordering due to strain effects.