Compositional homogeneity of metalorganic chemical vapor deposition grown III-V compound semiconductor epilayers

The compositional homogeneity of epitaxially grown layers of GaInAs, AlInAs, and GaAlInAs on InP substrates has been investigated using pulsed laser atom probe techniques. All the material characterized was shown by transmission electron microscopy to have a fine-scale contrast variation, however only some of the samples were found, using atom probe techniques, to show distinct deviations from compositional uniformity. The average composition measured from each of the layers was that of the lattice-matched composition intended during growth, however the composition varied locally, on a scale of typically 10–20 nm, from the mean composition by up to 5 at. %.