Atomic placement of Al on the GaAs {001}c(4×4)reconstruction determined by angle-resolved secondary-ion mass spectrometry

Abstract

The atomic structure of the initial Al/GaAs ͕001͖ c(4ϫ4) interface has been examined by angle-resolved secondary-ion mass spectrometry. We find that Al atoms adsorb to second layer As atoms and do not disrupt the surface reconstruction up to 1.0 ML of deposited Al when prepared in situ via molecular beam epitaxy. The Al atoms are found not to adsorb to first layer As atoms and do not dimerize on this surface. The structure is determined by comparing angular distributions of Al ϩ and Ga ϩ ions to molecular-dynamics simulations of the ion bombardment event.