Relation between Surface Composition and Electronic Properties of Native Oxide Films on an Aluminium-Copper Alloy Studied by DFT

Abstract

We performed a DFT modelling of Al2O3(001)/Al(001) and Al2O3(001)/Al2Cu(001) surfaces and of Al(010)/Al2Cu(010) interfaces covered with Al2O3(001). We focus on the electronic properties (work function, valence band and electronic gap) computed for the different models. We show that both on Al and Al2Cu, the oxide layer induces a significant increase in work function. The effect of the composition of the first metallic layer underneath the oxide film is also investigated. Cu enrichment under the oxide film induces an increase in work function, however less marked than the one caused by the oxide layer. We show that the work function increase is due to a charge transfer from the interfacial metal layer to the oxide layer. The same result is found at the oxidized Al(010)//Al2Cu(010) interface. The work function of the oxidized Al2Cu zone is higher than the one of oxidized Al.