  Resistive switching devices herald a transformative technology for memory and
computation, offering considerable advantages in performance and energy
efficiency. Here we employ a simple and scalable material system of conductive
oxide interfaces and leverage their unique properties for a new type of
resistive switching device. For the first time, we demonstrate an $\rm
Al_2O_3-TiO_2$ based valence-change resistive switching device, where the
conductive oxide interface serves both as the back electrode and as a reservoir
of defects for switching. The amorphous-polycrystalline $\rm Al_2O_3-TiO_2$
conductive interface is obtained following the technological path of
simplifying the fabrication of the two-dimensional electron gases (2DEGs),
making them more scalable for practical mass integration. We combine physical
analysis of the device chemistry and microstructure with comprehensive
electrical analysis of its switching behavior and performance. We pinpoint the
origin of the resistive switching to the conductive oxide interface, which
serves as the bottom electrode and as a reservoir of oxygen vacancies. The
latter plays a key role in valence-change resistive switching devices. The new
device, based on scalable and complementary metal-oxide-semiconductor (CMOS)
technology-compatible fabrication processes, opens new design spaces towards
increased tunability and simplification of the device selection challenge.
