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