The Role of Acoustic Wave Amplification in the Emission of Microwave Noise from InSb

The experimental evidence for the generation of microwave emission from InSb by acoustic amplification of thermal noise is reviewed. The conditions in which the electron-phonon interaction is likely to dominate over other possible physical mechanisms are discussed, with particular reference to crystallographic orientation and crystal geometry. The application of the small signal acoustic amplification theory is shown to lead to qualitative agreement between constant gain loci and emission threshold curves.