Angular dispersion of surface acoustic waves on (001), (110), and (111) GaAs

Abstract

The generalized surface, pseudosurface, and high-frequency pseudosurface acoustic waves propagating on (001), (110), and (111) surfaces of GaAs have been examined using Brillouin spectroscopy. The phase velocities of the surface acoustic waves were measured as a function of their propagating directions over the entire angular periods on the respective basal planes. Unlike the single dispersion curve arising from the branching from the generalized surface mode to the pseudosurface mode, commonly observed for anisotropic cubic crystals, two separate and distinct dispersion branches were recorded for these surface modes on the (001) surface. The complete dispersion branch of high-frequency pseudosurface acoustic waves on the (110) surface has been determined.