Resistive switching characteristics of solution-deposited Gd, Dy, and Ce-doped ZrO2 films

Several rare earth elements (Gd, Dy, and Ce) having different valence numbers were doped into a solution-synthesized ZrO2 film, and the corresponding resistive memory characteristics were discussed in relation to the oxygen vacancies and film microstructure. Pure and trivalent ion-doped ZrO2 films showed forming-free behavior, probably because of the large amount of inherent and additional dopant-incurred oxygen vacancies, respectively. In contrast, tetravalent Ce ion doping caused the forming process to be required and afforded stable long-term switching characteristics with a relatively large memory window, which is attributed to the dopant-enhanced crystallization/densification effect without excessive oxygen vacancy generation.