Polaronic Resistive Switching in Ceria‐Based Memory Devices

Abstract

AbstractResistive random access memory (RRAM), or memristors, operating with a voltage‐controlled low‐ and high‐resistance state (ON/OFF), are a critical component for next‐generation nanoelectronics. Most memristors are based on oxides, but the underlying working mechanism remains generally unclear. Using first‐principles calculations, it is revealed that it is polaron that acts as the conducting species to mediate the resistive switching process in CeO2, while the commonly believed oxygen vacancy (VO2+) plays only a secondary role in assisting polaron formation. Importantly, polaron and related complexes have desired low formation energies (≈−0.3 eV) and extremely small migration barriers (≈0.1 eV), to synergistically form conductive filaments in the CeO2 matrix with shallow electronic states near Fermi level, while VO2+ has a much higher migration energy and does not change the insulating nature of CeO2. A switching field is also estimated of ≈3 V between the ON/OFF states from the relative stability of VO2+, Hint+/Hsub+ (institutional/substitutional hydrogen) and polaron complexes in reference to Fermi level, which agrees with experiments. The proposed polaron‐based switching mechanism is general, paving the way for future understanding and design of multifunctional electronic nanodevices beyond RRAM.