Ion fractions in 6 keV Ne +, Ar + and Na + scattering from a GaAs(110) surface

We used Ion Scattering Spectrometry (ISS) with Time-of-Flight (TOF) analysis to study the neutralization of 6 keV Ne ⁺, Ar ⁺ and Na ⁺ backscattering from a flat and ordered GaAs(110) surface. At low incident angles an important contribution to the total (neutral + ion) backscattering spectra comes from quasi single collisions with As and Ga first layer surface atoms. We observed that the ion fraction in this contribution is strongly dependent on both the incident projectile and the target atom, suggesting that the violent collision plays an important role in the neutralization process. In order to interpret these dependencies we performed a calculation that discriminates the interaction of the projectile with the extended and localized states of the solid.