Brillouin scattering determination of the elastic constants in supported Ge films

Brillouin scattering from supported Ge films, prepared by rapid thermal processing chemical vapor deposition (RTPCVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques, is carried out in the backscattering geometry. The phonon spectra are analyzed and simulated by taking the ripple and elasto-optic coupling into account, which leads to an accurate determination of the elastic constants. It is found that these constants are strongly dependent on deposition methods. In addition, we have also studied the influence of the interdiffusion in the interfacial layer on the elastic properties.