Highly Controllable and Stable Quantized Conductance and Resistive Switching Mechanism in Single-Crystal TiO₂ Resistive Memory on Silicon

TiO₂ is being widely explored as an active resistive switching (RS) material for resistive random access memory. We report a detailed analysis of the RS characteristics of single-crystal anatase-TiO₂ thin films epitaxially grown on silicon by atomic layer deposition. We demonstrate that although the valence change mechanism is responsible for the observed RS, single-crystal anatase-TiO₂ thin films show electrical characteristics that are very different from the usual switching behaviors observed for polycrystalline or amorphous TiO₂ and instead very similar to those found in electrochemical metallization memory. In addition, we demonstrate highly stable and reproducible quantized conductance that is well controlled by application of a compliance current and that suggests the localized formation of conducting Magnéli-like nanophases. The quantized conductance observed results in multiple well-defined resistance states suitable for implementation of multilevel memory cells

A Low-Leakage Epitaxial High‑κ Gate Oxide for Germanium Metal–Oxide–Semiconductor Devices

Germanium (Ge)-based metal–oxide–semiconductor field-effect transistors are a promising candidate for high performance, low power electronics at the 7 nm technology node and beyond. However, the availability of high quality gate oxide/Ge interfaces that provide low leakage current density and equivalent oxide thickness (EOT), robust scalability, and acceptable interface state density (<i>D</i>_it) has emerged as one of the most challenging hurdles in the development of such devices. Here we demonstrate and present detailed electrical characterization of a high-κ epitaxial oxide gate stack based on crystalline SrHfO₃ grown on Ge (001) by atomic layer deposition. Metal–oxide–Ge capacitor structures show extremely low gate leakage, small and scalable EOT, and good and reducible <i>D</i>_it. Detailed growth strategies and postgrowth annealing schemes are demonstrated to reduce <i>D</i>_it. The physical mechanisms behind these phenomena are studied and suggest approaches for further reduction of <i>D</i>_it