Surface vibrational modes of Sb-terminated (110) surfaces of III-V semiconductors investigated by Raman spectroscopy

Abstract

We present a Raman study of surface vibrational modes on Sb-terminated GaAs(110), GaP(110), InP(110), and InAs(110) surfaces. The results for epitaxial Sb monolayers on GaAs(110) and GaP(110) are presented, which complement the previously published data on the surface vibrational modes of Sb/III-V(110). We extend the experimental determination of surface Raman scattering to a level that is more quantitative than that in the previous work by calculating difference spectra between the measured Raman data of monolayer terminated and clean surfaces. The eigenfrequencies and mode symmetries determined by Raman spectroscopy are compared to results from density-functional theory and density-functional perturbation theory calculations. The good overall agreement between experiment and theory allows us to assign the individual Raman peaks to characteristic eigenmodes of the monolayer structure. Most of the Raman peaks are associated with optical surface modes at the Brillouin-zone center, i.e., localized modes (surface phonons) and modes coupled to bulk phonons (surface resonances). In addition to these, other surface Raman peaks are detected and assigned to defect activated acoustic surface modes at the Brillouin-zone boundaries.