Influence of Homo- and Hetero-Junctions on the Propagation Characteristics of Radially Propagated Cylindrical Surface Acoustic Waves in a Piezoelectric Semiconductor Semi-Infinite Medium

Abstract

This paper theoretically investigates the influence of homo- and hetero-junctions on the propagation characteristics of radially propagated cylindrical surface acoustic waves in a piezoelectric semiconductor semi-infinite medium. First, the basic equations of the piezoelectric semiconductor semi-infinite medium are mathematically derived. Then, based on these basic equations and the transfer matrix method, two equivalent mathematical models are established concerning the propagation of radially propagated cylindrical surface acoustic waves in this piezoelectric semiconductor semi-infinite medium. Based on the surface and interface effect theory, the homo- or hetero-junction is theoretically treated as a two-dimensional electrically imperfect interface in the first mathematical model. To legitimately confirm the interface characteristic lengths that appear in the electrically imperfect interface conditions, the homo- or hetero-junction is equivalently treated as a functional gradient thin layer in the second mathematical model. Finally, based on these two mathematical models, the dispersion and attenuation curves of radially propagated cylindrical surface acoustic waves are numerically calculated to discuss the influence of the homo- and hetero-junctions on the dispersion and attenuation characteristics of radially propagated cylindrical surface acoustic waves. The interface characteristic lengths are legitimately confirmed through the comparison of dispersion and attenuation curves calculated using the two equivalent mathematical models. As piezoelectric semiconductor energy harvesters usually work under elastic deformation, the establishment of mathematical models and the revelation of physical mechanisms are both fundamental to the analysis and optimization of micro-scale surface acoustic wave resonators, energy harvesters, and acoustic wave amplification based on the propagation of surface acoustic waves.

Influence of Homo- and Hetero-Junctions on the Propagation Characteristics of Love Waves in a Piezoelectric Semiconductor Semi-Infinite Medium

“…It is shown that homogeneous junctions have relatively good temperature stability, but heterogeneous junctions are sensitive to a temperature change that may be explored for thermally manipulating piezotronic devices. Guo et al established the mathematical models of the propagation of radially propagated cylindrical surface waves in a PSC semi-infinite medium to investigate the influence of PN junctions on the dispersion and attenuation properties of the above waves [19]. It is found that PN junctions can be approximately treated as imperfect interfaces, which can enhance the width of band gaps of anti-plane elastic waves and the attenuation properties of surface waves, especially for high-frequency short-wavelength elastic waves.…”