  Using Rayleigh surface acoustic waves (SAW), the Young's modulus, the density
and the thickness of polycrystalline Silicon-Germanium (SiGe) films deposited
on silicon and SiO2 were measured, in excellent agreement with theory. The
dispersion curve of the propagating SAW is calculated with a Boundary Element
Method (BEM)-Model based on Green's functions. The propagating SAW is generated
with a nanosecond laser in a narrowband scheme projecting stripes from a mask
on the surface of the sample. For this purpose a glass mask and a liquid
crystal display (LCD) mask are used. The slope of the SAW is then measured
using a probe beam setup. From the wavelength of the mask and the frequency of
the measured SAW, the dispersion curve is determined point by point. Fitting
the BEM-Model to the measured nonlinear dispersion curve provides several
physical parameters simultaneously. In the present work this is demonstrated
for the Young's modulus, the density and the thickness of SiGe films. The
results from the narrowband scheme measurement are in excellent agreement with
separated measurements of the thickness (profilometer), the density (balance)
and the Young's modulus (nanoindenter).
