Abstract
A self-consistent semiclassical theory is given for explaining the characteristics of the interaction of electrons and holes with acoustic waves in intrinsic semiconductors. The ultrasonic absorption coefficient can be written as Λ=ΛR+ΛK, where ΛR is due to the change of the deformation potential energies of electrons and holes caused by their recombination, ΛK due to the change of the kinetic energy caused by the intraband transition. The formula of ΛR is identical with that used by Southgate in the analysis of his experiments, if the frequency at which ωτ=1 satisfies the inequality (ql)2<3(τ0⁄τ), where ω, q are the angular frequency and the wave number of acoustic waves, and l, τ0, τ are the mean free path, the intraband relaxation time, the lifetime of electrons or holes respectively. Under such condition as the frequency ω=1⁄τ satisfies (ql)2>3(τ0⁄τ), no absorption peak can be expected contrary to the simple phenomenological treatment: ΛR become smaller than the value of Southgate’s formula and is obscured by ΛK. As a whole, the characteristics of interaction is very similar with those in many-valley semiconductors. The acousto-electromotive force is too small to be detectable in experiments.
