Effects of Schottky junction on surface waves in a piezoelectric semiconducting film over a metal substrate

Shear horizontal (SH) waves propagating in a metal substrate covered with a transversely isotropic piezoelectric semiconductor thin film is analyzed in the present paper. The Schottky junction, which is created by the metal and the n-type piezoelectric semiconductor with a higher Fermi level, can be seen as an electrically gradient layer between the substrate and the thin film. The transfer matrix of the Schottky junction is derived by using Magnus series expansion and approximate laminated medium methods, respectively. The influences of the Schottky junction, semiconductor coupling, doping density, and electric boundary conditions on the dispersion and attenuation and the first three wave modes are discussed via numerical example. It reveals that numerical results obtained by these two methods are well matched and the existence of Schottky junction has less influence on the dispersion of SH surface wave although, but evidently influences on the attenuation. In particular, the mode shapes of electric potential, electric displacement, carrier perturbation density, and the electric current density are affected evidently by the existence of Schottky junction.