Electronic properties of antimony monolayers on III–V (110) surfaces: a comparative study by reflectance anisotropy spectroscopy and microscopic tight-binding calculations

A systematic investigation of the structural, electronic and optical properties (by means of Raman spectroscopy and reflectance anisotropy spectroscopy (RAS)) has been done for clean and antimony-covered (110) GaAs, InP, InAs, and GaP surfaces. We present here the theoretical interpretation of the experimental reflectance anisotropy spectra for InAs(110) and GaP(110) surfaces, both clean and Sb covered. The different contributions to the optical spectra, originating from surface-to-surface (SS), bulk-to-bulk (BB) and mixed surface-to-bulk (SB) and bulk-to-surface (BS) state transitions, are discussed in detail on the base of microscopic calculations. Good agreement of the theoretical results and experimental data allows us to clarify the origin of the surface optical modification during Sb adsorption. The appearance of strong excitonic effects for clean and Sb-covered GaP(110) surfaces is hypothised.