Improvement of switching uniformity in HfO_x-based resistive random access memory with a titanium film and effects of titanium on resistive switching behaviors

Abstract

In this study, the effects of the Ti layer on resistive switching behaviors of HfO x -based resistive switching random access memory (ReRAM) were investigated. After introducing a thin Ti layer (>10 nm) between the Ta and HfO x layers, both cycle-to-cycle uniformity within one cell and cell-to-cell uniformity were significantly improved. In addition, the higher ON/OFF ratio was obtained owing to the resistance increase in the high-resistance state, and a high device yield (>90%) also was achieved. The improvement of switching uniformity can be explained by the Ti doping effect, which is caused by the diffusion of Ti into the HfO x layer. In addition, the Ti layer had the effect of generating more oxygen vacancies in the HfO x layer, which led to the lowering of forming voltage (>2.6 V). To confirm the change in the amount of oxygen vacancies, X-ray photoelectron spectroscopy analysis was performed. The formation of the TiO x layer and the Ti doping effect are considered to contribute to the generation of more oxygen vacancies in the HfO x layer.

Unipolar resistive switching with forming-free and self-rectifying effects in Cu/HfO2/n-Si devices

“…Based on the phenomena described above, the resistive switching behaviors are agreement with conductive filament model very well. Generally speaking, there are metal CF 27,35-37 and oxygen vacancy CF [38][39][40] in the binary oxide dielectric such as HfO 2 film. Many studies have been reported that active electrodes such as Ag 4,41 and Cu [35][36][37] tends to migrate and form CF connecting with counter electrodes, playing an important role in resistive switching process.…”

Resistive switching phenomena: A review of statistical physics approaches

“…For example, most RS phenomena are accompanied by wide fluctuations in various switching parameters, including switching voltages, switching currents, and the resistance of a cell. [73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88] These fluctuations in switching parameters should be attributed to the diverse patterns of the conductive paths formed by CFs. Although reducing such fluctuations is the key challenge for commercial memory applications, 89 most microscopic theories cannot explain the fluctuations occurring in RS.…”

“…One of the major technical obstacles is the wide distribution of switching parameters, including switching voltages. [73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88] For example, Fig. 45(a) shows 100 I-V curves in Pt/NiO/Pt cells exhibiting typical unipolar switching.…”

Memristive Devices with Highly Repeatable Analog States Boosted by Graphene Quantum Dots

“…Also, the device‐to‐device variations are also improved by introducing GQDs into memristive devices, as shown in Figure S3 (Supporting Information). In addition, it is worth noting that the ON/OFF ratio of GQDMem is dependent on the compliance current and reset voltage . The comparison of On/OFF ratio between GQDMem and control memristors will be further analyzed in Figure .…”

“…In addition, it is worth noting that the ON/OFF ratio of GQDMem is dependent on the compliance current and reset voltage. [9,39,40] The comparison of On/OFF ratio between GQDMem and control memristors will be further analyzed in Figure 5.…”