Effect of an ultrathin SiO2 interfacial layer on the hysteretic current–voltage characteristics of CeOx-based metal–insulator–metal structures

It is shown in this work that the presence of an ultrathin (~ 1.5 nm) SiO2 interfacial layer reactively formed in between a thick (~ 20 nm) high-permittivity CeOx film and a metal NiSi2 bottom electrode in a metal–insulator–metal structure has remarkable consequences for the hysteretic current–voltage (I–V) characteristic of the device. Conductance values in the low resistance state (LRS) close to integer and half-integer values of the quantum conductance unit G0 = 2e2 / h, where e is the electron charge and h the Planck constant, reveal the formation of filamentary structures across the stack with bottlenecks of atomic dimensions. Even though the hysteretic behavior partially remains when the bottom electrode (Ti, TiN, or W) is changed, the LRS I–V no longer exhibits so well defined conductance levels as in the NiSi2 case. This distinctive behavior is attributed to the presence of the SiO2 switching layer. Supplementary post-breakdown I–V data obtained from Al/SiO2/Si capacitors supports this hypothesis.

► Resistive switching in CeOx-based metal-insulator-metal devices was investigated.
► Conductance quantization effects observed for NiSi2 bottom electrode.
► Model for the current-voltage characteristic based on the Landauer approach is proposed.