Nonlinear Interaction Between an Elastic Wave and Charge Carriers in a Piezoelectric Semiconductor Rod Aroused by a Dynamic Axial Force at an Endpoint

Wave-particle drag effect (WPDE) induced by the interaction between an elastic wave and the carriers in a piezoelectric semiconductor (PS) structure has already become a current hot issue in the field of acoustoelectric conversion. Most related studies are based on the linearized assumption that carrier concentrations are limited to present very small variations such that the nonlinear drift current term can be ignored at all. In this study, the nonlinear effect between an elastic wave and carriers in a PS rod is discussed in detail. The multi-field coupled nonlinear differential equations are numerically solved by finite element method. It is found that the electric transient disturbances are deviated from the standard harmonic distribution by comparing with the linear solutions. The carriers driven by the alternating electric field are more likely to accumulate at the crest when their drift movement motion is consistent with the propagation direction of the traveling wave. Oppositely, the troughs of the carriers tend to depletion due to the nonnegative property of the carriers. In addition, the nonlinear characteristics of the carriers and the dispersion properties of the coupled wave become stronger with the decreasing doping concentrations. These studies will provide guidance for theoretical analysis of wave propagating in PSs and design of acoustoelectric devices.