MBE GROWTH AND STRUCTURAL CHARACTERIZATION OF SI1-YCY SI1-XGEX SUPERLATTICES/

We report on the MBE growth and X-ray characterization of Si1-yCy/Si1- xGex superlattices (SLs). The concentrations and thicknesses of the la yers were chosen such as to get strain-symmetrized superlattices, latt ice-matched to the Si (001) substrates. In-situ RHEED investigations s howed increasing roughness during the growth of the Si1-yCy layers and a smoothing effect of the subsequent Si1-xGex layers. Further charact erizations comprised double and triple axis X-ray diffraction, X-ray r efraction (XRR), and atomic force microscopy (AFM). Dynamical simulati ons of the various X-ray configurations yielded the structural paramet ers of the SLs as well as information on the morphological and replica tion properties of the interfaces. With increasing carbon content we f ound an overall interface roughening concomitant with a significant de crease of the replication length. Lateral correlation length fits were compared with AFM-measurements, which give a more detailed picture of the interface morphology as long as the replication lengths are large .