Attenuation and Amplification of Hypersound by Mott Excitons in Semiconductors with Piezoelectric and Deformational Electron‐Phonon Interactions

Abstract

AbstractA calculation is made of the attenuation of hypersound by Mott excitons in semiconductors with piezoelectric and deformational electron‐phonon interactions taking into account 1. the complex band structure (anisotropy, many‐valleyness, degeneracy, spin‐orbit interaction); 2. the presence of many sorts of carriers and screening of the electron‐phonon interaction; 3. the possible change in the internal state of the exciton including its dissociation and formation from a pair; 4. the possible degeneracy and Bose‐Einstein condensation of the excitonic gas. It is proved that there is a real possibility of amplification of hypersound both by the excitonic gas, due to its de‐excitation and by the electron‐hole gas, due to the formation an exciton from a pair (at rather low temperatures). The resonant character of hypersonic attenuation by the excitonic condensate may serve as an agent for detecting the latter effect. The measurement of attenuation and emission frequencies allows the exciton binding energy and the main values of its effective mass tensor to be determined.