On dispersion and dissipation of elastic wave-fronts in piezoelectric semiconductors

Abstract

When an elastic wave propagates in piezoelectric semiconductors, the interaction between charge carriers and electric fields on the elastic wave-front (EWF) generates a coupled wave, termed the field-particle coupling wave (FPCW). The propagation speed of FPCW is usually greater than that of the corresponding elastic wave, causing that a preceding EWF is undoubtedly overtaken and influenced by those FPCWs emitted from the trailing EWF. Hence, the effect of FPCW on EWF is systematically investigated in this paper. Our numerical results indicate that the nonlinear feature of drift current causes the stronger dispersion behavior on EWF, while the dissipation behavior of EWF is only caused by the Joule heating effect. Furthermore, loading configuration significantly affects the dynamic characteristics of EWF via different behavior of EPCW. Under a sine-typed loading, the dispersion effect is confined to act on EWF itself with very tiny effects ahead of it. In contrast, a cosine-typed loading induces dispersion not only at the EWF itself but also in front of it. Thus, an interesting phenomenon shows a moving reversal barrier or a moving barrier layer just ahead of the EWF under a cosine-typed loading. We particularly note that the above two moving layers of barriers cannot leave from the leading end of EWF, which is similar as that of the Greek hero Antaeus who had to constantly draw energy from the Earth Mother. The study of dispersion and dissipation in elastic waves propagating in piezoelectric semiconductors is crucial for the R&D and performance enhancement of piezoelectric electronic devices.