Ion fractions in Ne+ scattering from a GaAs(1 1 0) surface

Ion scattering spectrometry with time-of-flight analysis is used to measure the ion fractions in 6 keV Ne+ projectiles scattered from a GaAs(1 1 0) surface for a broad incidence and observation angular range. The neutralization of the Ne+ ions is studied by using a Green’s function formalism to solve the time-dependent collisional process. The interacting system is described by a spin-less Anderson-like Hamiltonian where the valence and localized states of the surface are taken into account. Two important ingredients are incorporated in the theoretical model: the description of the reconstructed surface by using a molecular dynamics density functional theory in the local density approximation to calculate the local an partial density of states; and the calculation of the Hamiltonian interaction terms by considering the orientations of the projectile orbitals with respect to the reference frame provided by the surface. The results allow to infer that the different behaviour observed in the ion fractions of the projectiles scattered from As and Ga atoms can be mainly related to resonant neutralization processes that are strongly determined by the local electronic structure of the surface. The angular dependence of the ion fraction for two different scattering angles is analyzed.