Optical characterization of surface electronic and vibrational properties of epitaxial antimony monolayers on III-V (110) surfaces

The electronic and vibrational properties of InP(110). GaAs(110), GaP(110), and InAs(110) surfaces terminated with ordered Sb monolayers are studied by Reflectance Anisotropy Spectroscopy (RAS) and Surface Resonant Raman Spectroscopy (SRRS). In the RAS spectra of the monolayer covered surfaces optical anisotropies attributed to transitions of the electronic surface band structure of the monolayer can be identified. On all four substrates, prominent surface transitions are found in the photon energy range from 1.8 to 2.8 eV. The SRRS, on the other hand, is utilized to monitor surface vibrational modes of the monolayer terminated surfaces. The scattering cross section reveals a clear correlation to the surface transitions detected by RAS; for resonance condition to the surface electronic transitions maximum scattering efficiency occurs. This can be understood in terms of deformation potential scattering. Since the Sb monolayer vibrational modes modulate mainly the bonds of the first few atomic layers, the corresponding modulation of the polarizability is dominated by the surface electronic band structure.