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

GARCIA E.; C. GONZÁLEZ PASCUAL; E. C. GOLDBERG; J. E. GAYONE; E. A. SÁNCHEZ; O. GRIZZI

SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2003 vol. 541 p. 160 - 170

0039-6028

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