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 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 1=25° 3°and a relaxation of the rotated top layer toward the substrate by 0.1 0.05. The top layer reconstruction is essentially identical to that for GaAs(110) and InSb(110), but relaxed 0.05 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 K, whereas those for GaAs(110) and InSb(110) were obtained at T=150 K.