Elastic properties of a-Ge:H/Si and a-Ge: H/SiO2 heterostructures

Abstract Brillouin light scattering from Rayleigh and Sezawa surface acoustic modes in a-Ge: H films depositedf on both c-Si(100) and fused silica substrates has been exploited for studying the elastic properties of these heterostructures. Their effective elastic constants have been determined from a fit of the calculated dispersion curves to the measured sound velocities. We have found that the effective shear modulus C 44 is much lower that that of crystalline Ge. The decrease observed is of about ∼ 38% when the film is supported by c -Si and of about ∼ 44% when supported by fused silica. No appreciable modification of the effective elastic constant C 11 , with respect to crystalline Ge, has been observed.