  We present electrical and structural characterization of epitaxial
LaTiO3/SrTiO3 quantum wells integrated directly on Si(100). The quantum wells
exhibit metallic transport described by Fermi-liquid behavior. Carriers arise
from both charge transfer from the LaTiO3 to SrTiO3 and oxygen vacancies in the
latter. By reducing the thickness of the quantum wells, an enhancement in
carrier-carrier scattering is observed, and insulating transport emerges.
Consistent with a Mott-driven transition in bulk rare-earth titanates, the
insulating behavior is described by activated transport, and the onset of
insulating transport occurs near 1 electron per Ti occupation within the SrTiO3
well. We also discuss the role that structure and gradients in strain may play
in enhancing the carrier density. The manipulation of metal-insulator behavior
in oxides grown directly on Si opens the pathway to harnessing strongly
correlated phenomena in device technologies.
