ULTRASOUND ATTENUATION IN SUPERLATTICES

The ultrasound attenuation coefficient is evaluated for an ideal, peri odic array of quantum wells (superlattice) by taking matrix elements o f the electron-phonon interaction between basis states that are plane- wave combinations of finite quantum-well wave functions. Contributions due to intrawell electron-phonon scattering as well as due to interwe ll transfer were found. In addition, a contribution due to the interfe rence of intrawell and interwell electron-phonon scattering process is obtained. The total attenuation coefficient along the superlattice ax is is found to be dependent upon the electron wave number (or the dens ity of states) at the Fermi level.