Fig. 10

Reduced forming voltage in oxygen stoichiometry-engineered HfO₂-based RS devices. a Forming process in annealed polycrystalline HfO₂ according to the specific location. Low variation of forming voltage with thickness for oxygen deficient HfO_2–x film. b Model for the thickness dependence of forming voltage in stoichiometric (left) and oxygen deficient HfO_2–x (right). c Switching characteristics tuned in oxygen deficient t-HfO_2–x. Schematic model of filament formation in oxygen engineered HfO_x-based RS devices. a, b reproduced with permission from [228]. c reproduced with permission from [12]