Unipolar Resistive Switching Characteristics of a $ \hbox{ZrO}_{2}$ Memory Device With Oxygen Ion Conductor Buffer Layer

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
$^{\circ}\hbox{C}$
.