Vibrational Raman scattering from surfaces of III-V semiconductors: Microscopic and macroscopic surface modes

With ongoing instrumental improvements Raman spectroscopy (RS) is advancing into the study of surface vibrational modes of semiconductors. On compound semiconductors, like the IIIV's, two distinct types of surface modes occur, microscopic modes being vibrations confined to the surface and macroscopic modes penetrating much deeper into the bulk, dependent on the electromagnetic boundary conditions. Both mode types depend on surface properties, the microscopic ones on the atomic scale, and the macroscopic ones on the scale of the surface polariton wavelength. While the former one delivers surface atomic structure information, the latter one may be useful for instance to study the morphology of surfaces, such as the shape of semiconductor nanowires. We discuss Raman spectra obtained on the atomically well-defined III-V(110) model surfaces and recent results obtained on isolated III-V nanowires. The comparison of both gives insight in the capabilities of Raman scattering from surface phonons: The contributions of surface phonons, surface resonances, and macroscopic modes (Fuchs-Kliewer modes, surface phonon polaritons) to the Raman spectra become evident.