The anisotropy of the electronic structures of clean GaP(110) surface has been studied by high-resolution electron-energy-loss spectroscopy (HREELS) for loss energies ranging from the bulk band gap up to 7 eV. A clear azimuthal dependence of the energy-loss spectra was found, demonstrating the anisotropic nature of the electronic properties of this surface in this energy excitation region. The effect of the exposure to hydrogen was also investigated. The degree of anisotropy observed in the HREELS spectra is gradually reduced at increasing coverage, revealing the surface nature of the electronic states involved in the scattering processes. The results are compared with the existing data regarding this surface. The comparison with theoretical results allows us to assign the electronic surface states involved in the anisotropic electron-energy-loss properties.

• Received 27 October 1988

DOI:https://doi.org/10.1103/PhysRevB.39.5975