Joanna Millunchick

Atomic Surface Structure in Compound Semiconductor Alloys: Step Edge Diffusion in Compound Semiconductors

Collaborators: Professor Chris Pearson, University of Michigan- Flint
Sponsor: National Science Foundation
Thin GaAs films grown on lattice-matched In0.53Ga0.47As/InP(001) have been imaged by in vacuo scanning tunneling microscopy. We observe that the morphological evolution of these strained films depends on the deposition and diffusion of group III adatoms and the incorporation of As from the vapor, in addition to Asaro-Tiller-Grinfeld instabilities. We compare step edge densities to a model for the Ga adatom density and find that the absolute magnitude of the group V and group III fluxes has a strong effect on the number of adatoms on the surface, and thus the morphology of the films.
Highlights (Click an image for more information)
  • STM image of 2ML of AlAs/InP(001)

    A 1000 Å × 1000 Å STM image of 2 ML of AlAs grown on InP(001). The morphology is dominated by holes, as predicted by elastic strain energy. The patches of differing intensity observed on each terrace are regions of different reconstruction. These regions suggest that the composition is not uniform and are possibly a precursor to lateral composition modulation.