Propagation of microwave phonons in germanium

The effects of various kinds of interactions on the propagation of 9 GC microwave phonons in germanium have been studied experimentally. We will discuss phonon interactions 1) with conduction electrons in degenerate n - Ge, which produces attenuation of waves of specific polarization in particular directions of propagation, 2) with thermal phonons, which gives temperaturedependent ultrasonic attenuation, 3) with microwave phonons, which gives nonlinear effects.