Fermi-Level Pinning Engineering for Achieving High-Performance Ge-Based Resistive Memory With Ultrahigh Self-Rectifying Ratio (> 105)

In this work, we investigate the self-rectifying behaviors of the resistive random access memory (RRAM) fabricated on n-Ge substrates, featuring an ultrahigh rectifying ratio (> $10^{{5}}$ ), a high ON/ OFF ratio (>500), and low operation voltages. The excellent performances of the Ge-based RRAM in this study are attributed to the Fermi-level pinning (FLP) near the valence band edge of n-Ge through the localized conductive filaments in HfO2. In addition, the underlying mechanism of the FLP behaviors in RRAM on n-Ge substrates is discussed. The electrical properties of the self-rectifying RRAM, including superior data retention, excellent uniformity, decent switching speed, endurance, and robust read/write disturbance immunity, are characterized comprehensively. The FLP-induced superior rectifying behaviors and excellent electrical properties of the RRAM enable the potential application of the high-density nonvolatile memory.