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

Abstract

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 non-stoichiometric 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.

Interfacial Structure of Ti2AlN Thin Films on MgO(111)

“…Instead, Ti atoms attract electrons (from +1.23e to +0.29e and from +1.23 e to +0.96e for T 2 - and T 1 -terminated surfaces, respectively). This situation is similar to MgO(111) surface and was also observed in the calculations done for LaAlO 3 (0001) surface . The unbalanced charge accumulated at the surface will create a nonzero dipole moment and make the surface polarized.…”

Band alignment in LaAlO3/SrTiO3oxide heterostructures inferred from hard x-ray photoelectron spectroscopy

“…Indeed, several DFT calculations seem to indicate such a gap renormalization towards the interface. 23,28 The spectra are normalized to the same peak area. A chemically shifted Ti 3+ emission is observed, which reflects the extra Ti 3d electrons hosted at the interface.…”

Self-regulated growth of LaVO3 thin films by hybrid molecular beam epitaxy

“…New phenomena not observed in their bulk counterparts have been discovered, attributed to the electronic reconstructions that occur at polar/nonpolar interfaces 3 to compensate the charge discontinuity, such as in the case of LaVO 3 /SrTiO 3 , 4 valence state redistribution across polar interfaces, such as LaVO 3 /LaAlO 3 , 5 as well as chargestabilization of non-bulk-like phases formed at the interfaces between LaVO 3 and LaVO 4 . 6 Detailed growth studies of complex perovskite oxide thin films prepared by pulsed laser deposition (PLD), 7-9 molecular beam epitaxy (MBE), 10 sputtering, 11 and supporting first-principle calculations 12 have shown that the cation stoichiometry can dramatically impact the interface reconstructions. Therefore, the growth of correlated materials with excellent stoichiometry control is of critical importance to gain further insights into the intrinsic optoelectronic properties of these materials and ultimately their heterostructures.…”