Interaction of Conduction Electrons with Acoustic Waves in Many-Valley Semiconductors

Abstract

A semi-classical theory is given for explaining the characteristics of the interaction of conduction electrons with acoustic waves in many-valley semiconductors such as n -Ge. In general, the ultrasonic absorption coefficient can be written as \begin{aligned} \varLambda{=}\varLambda_{P}+\varLambda_{K}, \end{aligned} where \(\varLambda_{P}\) is due to the change of the deformation potential energy of electrons caused by net intervalley transitions. \(\varLambda_{K}\) due to the change of the kinetic energy caused by intravalley transitions. The acousto-electromotive force can be also written as \begin{aligned} F{=}F_{P}+F_{K}. \end{aligned} In the low frequency range the dominant terms are \(\varLambda_{P}\) and F P , but \(\varLambda_{K}\) and F K Predominate in sufficiently high frequency range. For longitudinal waves propagating in the direction and transverse waves propagating in the direction and polarized in the direction, F is identical with the formula of Weinreich-Sanders-White i...