High-k-rare-earth-oxide Eu2O3 films for transparent resistive random access memory (RRAM) devices

Fully transparent indium-tin-oxide/high-k-rare-earth-oxide Eu2O3/F-doped SnO2 devices that show stable bipolar resistance switching have been successfully fabricated. In addition to the transmittance of above 86% for visible light, high resistance ratio, good data retention and initial forming-free resistance switching behaviour were obtained in the transparent memory. The results of high-resolution spectroscopy and x-ray photoelectron spectroscopy analyses combining with the temperature dependence of resistance suggest that metallic Eu filaments are formed in the low-resistance state. Mechanism analysis indicates that the coexistence of oxygen vacancies and metallic Eu in the Eu2O3 films plays an important role in the forming-free resistive switching performance. The switching mechanism was attributed to formation/oxidation of filamentary and oxygen ion migration.