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

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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 non-stoichiometric 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 non-stoichiometrc 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.