Controlling Memristance and Negative Differential Resistance in Point‐Contacted Metal–Oxides–Metal Heterojunctions: Role of Oxygen Vacancy Electromigration and Electron Hopping

Abstract

Nonvolatile resistive switching memristance devices with a high on/off ratio are desirable for nanoelectronics such as resistive random‐access memory (RRAM) and in‐memory computing. Here, bipolar resistive switching in point‐contacted W/LaAlO3/SrTiO3(111) heterojunctions is reported, in which a Schottky barrier is formed at the metal/oxides interface, and 2d electron gas is formed at the interface of perovskite oxides. A negative differential resistance is observed in the RESET process. The result shows that the observed resistive switching is strongly associated with oxygen‐vacancies (OVs) in oxides with dominating contributions from electron hopping between OV trap sites, and can be controlled by oxygen annealing and electron injection. Remarkably, a method is developed by continuous RESET processes to increase the high resistance state by 1–3 orders of magnitude, with an on/off ratio enhanced from ≈10 to ≈104. The work provides a promising pathway to understand conduction mechanism of oxides memristors and promote its application in RRAM and in‐memory computing.