Rayleigh wave propagation in an elastic half-space with an attached piezoelectric semiconductor layer considering flexoelectricity and size-effects

To address the urgent demand for the miniaturization and multifunctional integration of high-frequency Rayleigh surface wave devices in 5G communication technology, the propagation characteristics of Rayleigh surface waves in an elastic half-space attached by a nanoscale piezoelectric semiconductor (PSC) thin layer with flexoelectricity and size-effects are systematically investigated. Based on the Hamiltonian principle, the elastic dynamic equations and Gauss's theorem of electrostatics are obtained. The eigenvalue problem is numerically solved with a genetic algorithm in MATLAB, and the dispersion properties are obtained. The effects of various key factors, including the flexoelectricity, inertia gradients, strain gradients, electric field gradients, PSC layer thickness, steady-state carrier concentration, and bias electric fields, on the propagation and attenuation characteristics of Rayleigh surface waves are analyzed. The results demonstrate that the increases in the flexoelectric coefficient and strain gradient characteristic length lead to an increase in the real part of the complex phase velocity, while the increases in the inertia gradient characteristic length, electric field gradient characteristic length, PSC layer thickness, and steady-state carrier concentration result in a decrease. Additionally, the bias electric fields significantly influence the Rayleigh surface wave attenuation. The present findings are crucial for the accurate property evaluation of miniaturized high-frequency Rayleigh wave devices, and provide valuable theoretical support for their design and optimization.