A comprehensive polarization Brillouin study has been carried out on the dependence of the phase velocities of the generalized surface, pseudosurface, and high-frequency pseudosurface acoustic waves on their propagation direction on the (001), (110), and (111) surfaces of InSb. The pseudosurface wave was found to have two angular dispersion branches arising from its respective 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 conventionally thought to be absent. An observation of high-frequency pseudosurface modes in InSb is also reported.

• Received 30 June 2000

DOI:https://doi.org/10.1103/PhysRevB.62.16665