Joanna Millunchick

I investigate the growth, stress, and morphological evolution of metamorphic buffer layers, grown on GaAs substrates by molecular beam epitaxy (MBE). The research focuses on GaAsSb and AlGaAsSb buffer layer designs. These layers seem to have higher nucleation rate of pure-edge dislocations, which are more efficient to relief the strain between the mismatched layers. Since pure-edge dislocations are sessile, the propagation of dislocations to the active region could be significantly reduced. I monitor the stress evolution in situ by multi-beam optical stress sensor (MOSS). This real time data is combined with detailed analysis of data obtained from x-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM).