We have investigated the transport properties of LaVO_{3}/SrTiO_{3} Mott-insulator-band-insulator heterointerfaces for various configurations. The (001)-oriented n-type VO_{2}/LaO/TiO_{2} polar discontinuity is conducting, exhibiting a LaVO3 thickness-dependent metal-insulator transition and low temperature anomalous Hall effect. The (001) p-type VO_{2}/SrO/TiO_{2} interface, formed by inserting a single layer of bulk metallic SrVO3 or SrO, drives the interface insulating. The (110) heterointerface is also insulating, indicating interface conduction arising from electronic reconstructions.

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We studied LaAlO3/SrTiO3 interfaces for varying LaAlO3 thickness by core-level photoemission spectroscopy. In Ti 2p spectra for conducting "n-type" interfaces, Ti 3+ signals appeared, which were absent for insulating "p-type" interfaces. The Ti 3+ signals increased with LaAlO3 thickness, but started well below the critical thickness of 4 unit cells for metallic transport. Core-level shifts with LaAlO3 thickness were much smaller than predicted by the polar catastrophe model. We attribute these observations to surface defects/adsorbates providing charges to the interface even below the critical thickness.