Generalized surface, pseudosurface, and high-frequency pseudosurface acoustic waves on (001), (110), and (111) InSb

A comprehensive polarization Brillouin study has been carried out on the de pendence of the phase velocities of the generalized surface, pseudosurface, and high-frequency pseudosurface acoustic waves on their propagation direc tion on the (001), (110), and (111) surfaces of InSb. The pseudosurface wav e was found to have two angular dispersion branches arising from its respec tive sagittal and shear-horizontal displacement components. The dispersion curve of the latter was found to extend into regions which are not bounded by the two transverse bulk mode branches, where pseudosurface waves are con ventionally thought to be absent. An observation of high-frequency pseudosu rface modes in InSb is also reported.