Raman scattering in strained Si1-xGex layers under hydrostatic pressure

The Si-Si Raman mode in Si1-xGex layers pseudomorphically strained to Si an d in bulk Si1-xGex was investigated as a function of externally applied hyd rostatic pressure. The experiments demonstrate that bulk elastic properties can be derived from the pressure-dependent Raman investigations of thin st rained hetero-epitaxial layers. Our experimental results are favourably ana lysed using linear interpolation for the components of elastic stiffness te nsor of the Si1-xGex compounds. It was found that the pressure derivative o f strained Si1-xGex increases with the Ge concentration. Our analysis sugge sts that the Gruneisen parameter for strained Si1-xGex is higher than expec ted from Linear interpolation between the Si and the Ge values and that it has slight negative pressure dependence.