  We fabricated high-mobility {\delta}-doped structures in SrTiO3 thin films in
order to investigate the low temperature electronic transport properties of
confined carriers in this system. An enhancement of the electron mobility above
the bulk value was observed as the doped layer thickness decreased. High-field
Hall measurements revealed that this mobility enhancement originates from
higher-mobility electrons in the undoped clean regions, which have
quantum-mechanically broadened from the doped layer. Because of the absence of
apparent lattice misfit between the layers, this structure is highly suitable
for investigating two-dimensional electron gases in SrTiO3.
