On elastic wave propagation in piezoelectric semiconductors with coupled piezoelectric and semiconductor properties

Coupling of piezoelectric and semiconducting properties can stimulate a field-particle coupling wave (FPCW) between electric field and charge carriers on an elastic wave-front (EWF) propagating in a piezoelectric semiconductor. The wave velocity of a FPCW is usually greater than the EWF as vibration frequency rises such that carrier behavior on and in front of the EWF will be disturbed in advance. This interaction between two waves can stimulate a few novel dynamic features which are of obvious significance for the research and development of innovative piezoelectric electronic devices. Hence, we firstly established a dynamic model on the propagation processes of elastic waves in piezoelectric semiconductors and developed an alternately iterative algorithm between piezoelectric and semiconducting properties in this paper. Then, the propagation behavior of an elastic wave in an n-type ZnO rod was taken as an example to elucidate the dispersion and dissipation arising from the coupling between electric field and charge carriers. It was found that the action of a FPCW on the EWF can stir up previously undiscovered bizarre features in the following two aspects. One is the energy transfer between different frequency wave components from low-order to high-order vibration modes implemented by the flow of charge carriers, where the transfer process bears a resemblance story to the ‘vacated room’ operation in Hilbert's paradox of the Grand Hotel. The other more intriguing one is that when a tensile/compressive deformation signal is input, an opposite phase signal will be induced at the leading edge of the EWF by the FPCW through the inverse piezoelectric effect, meaning the appearance of a compressive/tensile signal in front of the input tensile/compressive one. The reason to appear such a phenomenon is that the electric field phase of the FPCW is precisely opposite to the one on the corresponding EWF. Evidently, the present studies will advance the integration and development of elastic dynamics and semiconductor physics, thereby providing valuable guidance for the research and development of new electronic devices.