Density functional theory study on the formation mechanism and electronic properties of two-dimensional electron gas in LaInO3/BaSnO3 heterostructures with ferroelectric engineering

Abstract

Compared to the well-studied LaAlO3/SrTiO3 heterostructure (HS), the regulation mechanism of ferroelectric on the interfacial properties of LaInO3/BaSnO3 HS remains relatively unexplored. Here, we investigate the interfacial properties of the LaInO3/BaSnO3 HS models with the BaTiO3 ferroelectric film on different positions and with different ferroelectric polarization directions and intensities using first-principles density functional theory calculations. Our results reveal that the BaTiO3 film deposited on the top of LaInO3/BaSnO3 HS can significantly improve the interfacial electron density of the HS. Moreover, the ferroelectric polarization (electric field) direction and intensity of the upper BaTiO3 film play an important role in optimizing the interfacial electronic property of LaInO3/BaSnO3 HS. When the direction of the electric field in the BaTiO3 film is the same as that in the LaInO3 film, it provides an extra force to drive the electron transfer from the surface to the (LaO)+/(SnO2)0 interface. The largest interfacial charge density is 1.56 × 1014 cm−2 in BaTiO3(−0.005)/LaInO3/BaSnO3 HS. When the direction of the electric field in the BaTiO3 film is opposite to that in the LaInO3 film, the force from the LaInO3 film is counteracted by the BaTiO3 film, resulting in less electron transfer to the (LaO)+/(SnO2)0 interface. The interfacial charge density in BaTiO3(+0.005)/LaInO3/BaSnO3 HS is approximately one-tenth of that in BaTiO3(−0.005)/LaInO3/BaSnO3 HS. These findings provide new insights into ferroelectric-dependent interfacial phenomena and offer valuable guidance for designing functional perovskite oxide interfaces.