  Two dimensional electron gases (2DEGs) formed at the interfaces of oxide
heterostructures draw considerable interest owing to their unique physics and
potential applications. Growing such heterostructures on conventional
semiconductors has the potential to integrate their functionality with
semiconductor device technology. We demonstrate 2DEGs on a conventional
semiconductor by growing $GdTiO_3-SrTiO_3$ on silicon. Structural analysis
confirms the epitaxial growth of heterostructures with abrupt interfaces and a
high degree of crystallinity. Transport measurements show the conduction to be
an interface effect, with $\sim 9\times 10^{13} \; cm^{-2}$ electrons per
interface. Good agreement is demonstrated between the electronic behavior of
structures grown on Si and on an oxide substrate, validating the robustness of
this approach to bridge between lab-scale samples to a scalable,
technologically relevant materials system.
