Vacancies at LaAlO3 thin films: A 2D electron gas at the surface

• We study the properties of defects in LaAlO3 surfaces through ab initio calculations.
• We observe a tendency for vacancies to be localized at the surface of the films.
• Depending on the defect, we observe that holes or electrons are localized at the surface.
• This kind of localisation might lead to the formation of a 2D electron gas.

We have performed first principles calculations, based on the Density Functional Theory (DFT), to study the relative stability of Lanthanum, Aluminum and Oxygen vacancies at LaAlO3 thin films, and their electronic properties. In general, the formation energies of vacancies are smaller at the surface, which indicates a larger population of these defects in this region. We show that these defects can significantly alter the electronic properties of the surface and that electron gases at the surface of these films might occur, depending on the localisation of electrons or holes generated by these defects.