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Resistive switching in single crystal anatase TiO2 grown by atomic layer deposition on Si (001) with an epitaxial single crystal SrTiO3 buffer layer is characterized and analyzed. Although switching occurs via a valence-change mechanism involving motion of oxygen vacancies, electrical characteristics highly reminiscent of electrochemical metallization memories – low leakage current in the high-resistance state, highly linear current-voltage characteristics in the low-resistance state, and a very high on/off current ratio – are observed. We postulate that these characteristics may be associated with formation of Ti n O2n-1 Magnéli or Magnéli-like nanophases in the low-resistance state. In addition, quantized conductance is observed in the low-resistance state, with the number of conducting ballistic channels being highly controllable via application of different compliance currents during the memory SET process. For compliance currents of 10-200µA, low resistance state conductances corresponding to 1 to 4 conductance channels, controllable to within a single quantum of conductance, are observed.

Integration of functional oxides with semiconductors opens ways of creating novel hybrid architectures. However, epitaxy of these different types of materials brings challenges unlike those encountered in traditional semiconductor epitaxy. In this paper we will discuss our recent work on monolithic integration of perovskite oxides SrTiO3 and BaTiO3 on Si(001) and Ge(001), and the use of these pseudosubstrates to integrate other functional oxides using molecular beam epitaxy (MBE) and atomic layer deposition (ALD).

We present theoretical and experimental studies of three oxide heterostructures: LaAlO3/EuO heterojunction, Fe/BaTiO3/Pt superlattice and epitaxial LaCoO3 on (100)-oriented silicon. We use density functional theory (DFT) to predict the physical properties of the heterostucture and molecular beam epitaxy (MBE) to realize it in practice. We predict spin polarized two dimensional electron gas at the LaAlO3/EuO interface, linear magnetoelectric effect in a Fe/BaTiO3/Pt superlattice, and predict and demonstrate experimentally strain stabilized ferromagnetism in LaCoO3 on silicon.