Strain In Epitaxial Si/SiGe Graded Buffer Structures Grown On Si (100), Si(110) And Si (111) : A Raman Spectroscopy Study

摘要

We report preliminary results on the Raman characterization ofrnstrained-Si films pseudomorphically grown on (001), (110) andrn(111) SiGe virtual substrates. Because the relation between strainrnor stress and the Raman frequencies are complex, we first derivernthe strain-shift coefficients for the different substrate orientationsrnconsidered in this work. Then, visible and near-UV Ramanrnspectroscopies were used to extract the in-plane lattice parameterrnof the virtual substrate and the strain in the thin silicon epitaxialrnlayers grown on top. Finally, we investigated the in-plane strainrndistribution in strained Si/SiGe buffer layers grown on (110) andrn(111) silicon substrates by Raman imaging. In-plane strainrnfluctuations are observed both in the epilayer and the virtualrnsubstrate for all substrate orientations.