Two-dimensional electron gases (2DEGs) at oxide interfaces may exhibit unique properties, including effects from strong electron correlations, extremely high electron densities, magnetism, and 2D superconductivity. This article discusses routes to high-mobility 2DEGs in complex oxide heterostructures, with a particular focus on 2DEGs that involve transport in SrTiO. We discuss what is known about the electronic states in SrTiO 2DEGs, both experimentally and theoretically. Examples from the current literature are summarized.


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