Electronic charge redistribution in LaAlO3(001) thin films deposited at SrTiO3(001) substrate: First-principles analysis and the role of stoichiometry

We present a comprehensive first-principles study of the electronic charge redistribution in atomically sharp LaAlO3/SrTiO3(001) heterointerfaces of both n and p types allowing for nonstoichiometric composition. Using two different computational methods within the framework of the density functional theory (linear combination of atomic orbitals and plane waves) we demonstrate that conducting properties of LaAlO3/SrTiO3(001) heterointerfaces strongly depend on termination of LaAlO3(001) surface. We argue that both the polar catastrophe and the polar distortion scenarios may be realized depending on the interface stoichiometry. Our calculations predict that heterointerfaces with a nonstoichiometric film-either LaO-terminated n type or AlO2-terminated p type-may exhibit the conductivity of n or p type, respectively, independently of LaAlO3(001) film thickness.