Resistive switching in TiO2-based metal–insulator–metal structures with Al2O3 barrier layer at the metal/dielectric interface

• Pt/Al2O3/TiO2/TiN bilayer structures were prepared using atomic layer deposition.
• Two-step forming process led to stable repetitive bipolar resistive switching.
• Switching parameters could be effectively tuned by current compliance during SET.
• Endurance of 104 pulses was obtained for structures with 3 & 4 nm of Al2O3.
• Switching takes place in Al2O3 while TiO2 acts as an oxygen vacancy reservoir.

In this work we systematically study the effect of the Al2O3 barrier layer thickness on the resistive switching properties of Al2O3/TiO2 bilayer grown by atomic layer deposition in the Pt/Al2O3/TiO2/TiN stacks. It was found that an Al2O3 layer of a certain thickness is essential to stabilize the resistive switching parameters while these can be further tuned by current compliance during SET. A two-step forming process was required to achieve stable repetitive bipolar switching loops. The endurance of 104 readings of alternating resistance states was obtained for structures with 3 and 4 nm of Al2O3 during pulsed measurements. Forming was performed also at elevated temperatures using constant voltage stress. It was found that the switching is filamentary and happens in the Al2O3 layer while TiO2 is acting as an oxygen vacancy reservoir.