Hard x-ray photoemission spectroscopy of LaVO3/SrTiO3: Band alignment and electronic reconstruction

A heterostructure consisting of the Mott insulator LaVO3 and the band insulator SrTiO3 is considered a promising candidate for future photovoltaic applications. Not only does the (direct) excitation gap of LaVO3 match well the solar spectrum, but its correlated nature and predicted built-in potential, owing to the nonpolar/polar interface when integrated with SrTiO3, also offer remarkable advantages over conventional solar cells. However, experimental data beyond the observation of a thickness-dependent metal-insulator transition are scarce and a profound, microscopic understanding of the electronic properties is still lacking. By means of soft and hard x-ray photoemission spectroscopy as well as resistivity and Hall effect measurements we study the electrical properties, band bending, and band alignment of LaVO3/SrTiO3 heterostructures. We find a critical LaVO3 thickness of five unit cells, confinement of the conducting electrons to exclusively Ti 3d states at the interface, and a potential gradient in the film. From these findings we conclude on electronic reconstruction as the driving mechanism for the formation of the metallic interface in LaVO3/SrTiO3.

Automated summary

The heterostructure of LaVO3 and SrTiO3 shows promise for future photovoltaic applications due to their matching excitation gap and correlated nature at the interface. However, there is still a lack of experimental data and profound understanding of the electronic properties of the heterostructure.