Self-organized vertical superlattices in epitaxial GaInAsSb

Self-organized superlattices are observed in GaInAsSb epilayers grown nominally lattice matched to vicinal GaSb substrates. The natural superlattice (NSL) is detected at the onset of growth and is inclined by an additional 4° with respect to the (001) terrace of the vicinal GaSb substrate. This tilted NSL intersects the surface of the epilayer, and the NSL period is geometrically correlated with the periodicity of surface undulations. While the underlying driving force for this phase separation arises from solution thermodyamics, the mechanism for the self-organized microstructure is related to local strain associated with surface undulations. By using a template with surface undulations, the tilted NSL can be induced in layers with alloy compositions that normally do not exhibit this self-organized microstructure under typical growth conditions.