Rayleigh wave in layered piezoelectric semiconductor with consideration of PN junction effects

In this paper, analytical solutions for Rayleigh wave in a transversely isotropic piezoelectric semiconductor (PSC) substrate with a covering layer of different type doping are obtained. The PN junction (called also the depletion layer), which is created by the diffusion and drifting due to the different doping type of the substrate and the covering layer, can be considered as an electrically gradient layer between the covering layer and the substrate. Making use of the state transfer equation method, the transfer matrix of the state vector of the depletion layer is derived mathematically. Based on the numerical calculations, we investigate the physical influences of the covering layer, electric boundary conditions and doping concentrations on the dispersion and attenuation, and the effects of PN junction on the wave-mode shapes. Our results show that the semiconductor will slow the Rayleigh waves and induce the attenuation. Both the phase velocity and attenuation are dependent upon the frequency. The existence of PN junction has less influences on the dispersion and attenuation but relatively large influences on the wave-mode shapes, especially, on the electric potential, carriers concentration, electric displacement, and the current density of carriers.