Abstract：Piezoelectric semiconductors (PSs) have the physical properties of both piezoelectric and semiconductor materials. Devices and structures based on PSs have recently drawn particular attention due to their potential applications in multi-functional electronic devices. The core property of PSs is the interaction between the internal electric field and the charge carrier when under a mechanical force or a bias voltage. In the processing and application of PSs, the existence of initial stress is inevitable. At the same time, the initial stress is usually applied in the manufacturing process in order to prevent brittle fracture of materials. In this paper, the propagation behavior of shear-horizontal (SH) waves in an infinite n-type PS plate with initial stress is studied. The linear macroscopic theory of PSs is used. Based on the three-dimensional equations, the elastic surface wave problem is converted into a homogeneous linear eigenvalue system. Finally, making use of the boundary conditions on the top and bottom surfaces of the PS plate, a transcendental equation that determines the dispersion relation is obtained analytically. Numerical examples are presented to systematically study the effect of boundary condition, steady-state carrier density, plate thickness, and initial stress on the wave speed and attenuation of SH wave. In addition, SH wave propagation in two different PS materials under initial stress is discussed. It is found that the real and imaginary parts of wave velocity under short-circuit are correspondingly smaller than open-circuit boundary. The SH wave characteristics in the PS plate are the same as that in the corresponding piezoelectric plate when the steady-state carrier density is small (the semiconductor properties can be ignored). The results also show that the effect of small initial stress on phase velocity is negligible, and the wave speed decreases sharply when the initial stress reaches a certain value. Similarly, attenuation increases gradually as the initial stress becomes large enough. The calculation results in this paper could be helpful as theoretical guidance when designing PS surface acoustic wave devices.
2022, Vol. 43 
