Generation of nonequilibrium phonons in semiconductors and dielectrics by a pulse-heated metallic film: Model and experiment

Characteristics of a phonon generator in the form of a pulse-heated metallic film, viz., the time dependences of the film temperature and the kinetics of phonon ejection from the film into a substrate, are considered. The time dependences of the film temperature are calculated for cadmium telluride, diamond, and silicon substrates. It is shown that the duration of film cooling substantially exceeds the heating pulse length and the film continues to generate phonons with lower frequencies at the end of heating pulse. The inference is drawn that the film cooling should be correctly taken into account in analysis of the propagation of nonequilibrium acoustic phonons, specifically for phonon processes occurring in nanostructures.