Influence of the Thickness of TiO2/TiO2-x Layers on the Behavior of a Memristor Device

Memristors have been extensively investigated as the fourth fundamental circuit element. Titanium oxide is a common material used to fabricate memristors. In this paper, we investigated the influence of the thickness of the oxide active layer on the Al/TiO2-x/TiO2 /heavily doped electrode memristor architecture. An insulating TiO2 thin-film was deposited using an atomic layer deposition system, and TiO2-x active layers of 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, and 30 nm, respectively, were deposited using an RF sputtering technique. The conductivity and crystallinity of the oxygen vacancy based TiO2-x/TiO2 active layers were observed using atomic force microscopy. When the electrical characteristics of the memristor were evaluated, the 10 nm thick active layer memristor exhibited the most complete repeatable bipolar nonvolatile switching behavior, with an I-V curve of -3 to 3 V. The characteristics of the fabricated nonvolatile memory devices were confirmed by measuring the retention stability of the 10 nm thick active layer based device, which was judged to be the most suitable thickness ratio. Moreover, the endurance number of the ON and the OFF states of the fabricated device was maintained even when the measurement was performed for 1,000 seconds. This performance is indicative of potential applications in next-generation electronic memory devices.