Creating a two-dimensional hole gas in a polar/polar LaAlO3/KTaO3 perovskite heterostructure

Abstract

A two-dimensional hole gas (2DHG) at the perovskite oxide interface is of great interest because of its promising applications in next-generation nanoelectronics. Here we report the possibility of producing a 2DHG at the p-type (AlO₂)⁻/(KO)⁻ interface in the LaAlO₃/KTaO₃ heterostructure (HS) and demonstrate the formation energies of oxygen vacancies in the HS using first-principles density functional theory calculations. The pristine p-type LaAlO₃/KTaO₃ interface is intrinsically conducting with much higher interfacial charge carrier density and there does not exist a critical film thickness for the insulator-to-metal transition. However, under oxygen-poor conditions, oxygen vacancies are likely to form at the interfacial TaO₂ layer and on the surface LaO layer, destroying the 2DGH at the interface. Our results demonstrate an alternative way to produce a 2DHG in the LaAlO₃/KTaO₃ HS with careful control of oxygen vacancy formation.