Dynamical analysis of low-energy-electron-diffraction intensities from GaP(110)

An analysis of the structure of the (110) surface of GaP is performed by comparing dynamical calculations of elastic low-energy electron diffraction (ELEED) intensities with those measured at $T=300\mathrm{}$ K. Prior analyses of ELEED intensities from compound semiconductor surfaces are extended by considering both energy-independent (Slater) and energy-dependent (Hara) models of the exchange potential and by utilizing $R$-factor methods to assess the quality of the description of the measured intensities by the calculated ones. A description of the measured intensities is achieved which is as good as the best obtained earlier for analogous surfaces of other compound semiconductors: i.e., GaAs(110), InSb(110), InP(110), and ZnTe(110). The resulting best-fit structures consist of single-layer reconstructions characterized by a rotation angle of ${\omega }_1=25\mathrm{}°\pm 3°$ and a relaxation of the rotated top layer toward the substrate by 0.1 ± 0.05 Å. The top layer reconstruction is essentially identical to that for GaAs(110) and InSb(110), but relaxed 0.05 Å closer to the substrate. In contrast to these two surfaces, however, no evidence is obtained for second-layer reconstructions on GaP(110), a result which may be due to the fact that the ELEED intensity data for GaP(110) were acquired at $T=300\mathrm{}$ K, whereas those for GaAs(110) and InSb(110) were obtained at $T=150\mathrm{}$ K.