Unipolar Resistive Switching Characteristics of a Memory Device With Oxygen Ion Conductor Buffer Layer

摘要

Oxygen ion migration is an important factor in the formation and rupture of a conducting filament to cause resistive switching (RS) behavior. A calcium oxide-doped zirconium oxide $( hbox{CaO:ZrO}_{2})$ oxygen ion conductor buffer layer is introduced between the $hbox{Ti/ZrO}_{2}$ interface of conventional $hbox{Ti/ZrO}_{2}/hbox{Pt}$ memory devices to improve their unipolar RS properties. Increasing the CaO doping concentration to 2 mol% introduces higher oxygen vacancy content within the $hbox{CaO:ZrO}_{2}$ buffer layer, leading to higher oxygen ion conductivity. This allows more oxygen ions to migrate from the oxygen reservoir laterally and vertically across the 2-mol% $hbox{CaO:ZrO}_{2}$ buffer layer to the region where the conducting filament forms and ruptures. Therefore, the Ti/2-mol% $ hbox{CaO:ZrO}_{2}/hbox{ZrO}_{2}/hbox{Pt}$ device in this letter exhibits good endurance, high-speed switching (50 ns) without soft errors, stubborn nondestructive readout, and stable retention at 150 $^{circ}hbox{C}$.