ABSTRACTInterface mixing between the Ge and Si layers in symmetrically strained SimGem superlattices occurs during post growth thermal anneals. Interdiffusion coefficients were obtained from intensity changes in the low angle superlattice x-ray satellites on samples with nominal periodicities between 1.4nm and 5.6nm. A common activation energy of 3.0±0.1 eV was found. The bulk interdiffusion coefficients for SimGem were derived since measurements were made on samples with different layer thicknesses. Intermixing appears to occur by diffusion of Si atoms into the Ge layers via a vacancy mechanism. Raman scattering measurements support this process as well as the formation of Si1−xGex, alloy layers during the anneals.
ABSTRACTWe report Raman scattering measurements on poly-3-heptylthiophene and poly-3-undecylthiophenes both on resonance and preresonance conditions. We have studied different samples as solutions ,solution cast films and electrosynthetized as grown films. Our results indicate that the vibrational frequency of the mode which is strongly coupled to the π - π* electronic transition is sensible to “small” torsions between thiophenes rings , which do not necessarly interrupt completely the conjugation path.
Evidence for hydrogen transport in deuteratedLiBH4from low-temperature Raman-scattering measurements and first-principles calculations
