Improvement Of Resistive Switching Characteristics Research Articles

Effect of UV irradiation on the resistive switching characteristics of low-temperature solution-processed ZrO2 RRAM

This paper presents the fabrication of a solution-processed ZrO2 resistive random access memory (RRAM) device with low-temperature UV irradiation and the effect of UV irradiation on the resistive switching (RS) characteristics. The ZrO2 switching layer was deposited by spin-coating zirconium acetylacetonate (Zr(C5H7O2)4) precursor in an ethanol solvent; the maximum process temperature was 150 °C. The RS characteristics of the fabricated device were unstable for up to 2 h UV irradiation, but they improved after 4 h or longer UV irradiation. The 4 h and 8 h UV-irradiated devices show stable RS even after 200 dc switching cycles and long retention over 104 s. The improvement of RS characteristics caused by different UV irradiation times can be attributed to the reduction of the hydroxyl group (M–OH) and the formation of enhanced metal-oxide bonds (M–O) of the ZrO2 thin films, based on field emission scanning electron microscope and x-ray photoelectron spectroscopy analysis. This research suggests a promising approach to fabricate oxide thin films with good RS characteristics at low temperatures which has high potential to be extended to future flexible RRAM devices.

Improvement of Resistive Switching Characteristics of Titanium Oxide Based Nanowedge RRAM Through Nickel Silicidation

Low operation power and high endurance of resistive random access memory (RRAM) as a synaptic device are critical parameters for in-memory computing applications. Yet, high power consumption and reliability issue of silicon bottom electrode (BE) RRAM hinder its commercialization as a synaptic device. In this experiment, we report on the improvement of switching characteristics of silicon BE nanowedge RRAM via the Nickel (Ni) silicidation process. Existing highly doped Si-BE forms a SiO2 interfacial layer (IL) during a switching layer deposition and increases an effective thickness, leading to increased voltage drop within the RRAM device and large cycle-to-cycle variations. By siliciding the Si-BE with Ni, the issue of IL formation is removed and the resistance of metallic NiSi BE is further reduced compared to Arsenic (As <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ) doped Si BE. Both dc and ac analyses of the fabricated NiSi-BE nanowedge RRAM have shown the reduction of overshoot and switching current down to 55% of the original value. Transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS) analysis convinced the formation of NiSi BE. In addition, gradual switching characteristics, uniform low resistance state (LRS), and better endurance of NiSi-BE nanowedge RRAM enable the Si compatible approach to fabricate a large-size RRAM cross-point array for utilization in hardware-implemented neuromorphic computing applications.

Annealing effects on resistive switching of IGZO-based CBRAM devices

In this study, the impact of post-oxide deposition annealing on performance of IGZO-based conductive-bridging random access memory (CBRAM) is reported. It is found that besides the distinct reduction in resistive switching parameters of SET/RESET voltages, their dispersions, and the resistance ratio of high-resistance state to low-resistance state can be improved after N2 annealing. The annealing effects on enhancing of the resistive switching properties are investigated by x-ray photoelectron spectra. It can be considered that the formation of the filament is better controlled by the increase of oxygen vacancies in the switching layer, which is the main reason for the improvement of resistive switching characteristics.

Improvement of Resistive Switching Characteristics in Zinc Oxide-Based Resistive Random Access Memory by Ammoniation Annealing

In this experiment, the electrical performance of zinc oxide based-resistive random access memory (RRAM) is successfully improved by using annealing in ammonia hydroxide solution at low-temperature and high pressure to complete ammonium-doped ZnO based-RRAM. The results of material analysis indicate that using CO2 as ammonia hydroxide carrier during the annealing process leads to the reduction in dangling bond density. This can be clearly observed in the decrease in breakdown voltage during the forming process and a lower operating current during operation. Furthermore, in this ammonium-doped ZnO based-RRAM, we study the molecular doping of NH3 in ZnO, where the endurance and retention properties are improved as well. These improvements can be attributed to the higher concentration of nitrogen in the switching layer, which can effectively control the active oxygen ions during the operation process.

Effect of Interface Layer Engineering on Resistive Switching Characteristics of ZrO2-Based Resistive Switching Devices

An intentionally introduced interface layer in the resistive random-access memory (RRAM) devices play an important role in the improvement of resistive switching characteristics. In this paper, the resistive switching characteristics of ZrO2-based RRAM devices by inserting a thin TiO2 interface layer between electrodes and ZrO2 resistive switching layer were investigated. Compared with the Cu/ZrO2/Pt and Cu/ZrO2/TiO2/Pt devices, the Cu/TiO2/ZrO2/Pt and Cu/TiO2/ZrO2/TiO2/Pt devices showed much improved programing voltages, including lower forming voltage and lower set voltage. Moreover, the reset current was also improved. These results indicate that the TiO2 interface layer between the anode electrode and the resistive switching layer plays an important role in improving device performance.

Resistive switching characteristics of Titanium doping HfO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; memory cell under different annealing treatment

We fabricated resistive random access memory (RRAM) devices with Titanium doping HfO2 as the switching layer by magnetron sputtering and lithography technology. Resistive switching (RS) characteristics of HfTiO memory devices annealed under N2 and O2 ambient were investigated in this work. It was found that the improved RS properties were obtained in N2 annealing atmosphere, which showed larger RS window as well as improved uniformity for the RS parameters, while the device in O2 annealed atmosphere was the opposite. To clarify the effect of annealing treatment on the devices in various atmospheres, X-ray photo spectra and conduction mechanism, which are related to the RS properties were analyzed. It can be induced the increase of oxygen vacancies in the switching layer by N2 annealing treatment, which was benificial to the connection/ rupture of the conductive filament, was the main reason for the improvement of RS characteristics.

Improvement of Resistive Switching Characteristics in Solution- Synthesized Al, Cr, and Cu-Doped TiO2 Films

Improvement of Resistive Switching Characteristics in Solution- Synthesized Al, Cr, and Cu-Doped TiO2 Films

Improvement of Resistive Switching Characteristics by Thermally Assisted Forming Process for $\hbox{SiO}_{2}$-Based Structure

After high-temperature forming (HTF) and room-temperature forming treatments, the resistive switching behavior gets some improvements. The switching ratio is enhanced as the device undergoes the HTF process. Through the conduction mechanism analyses in the high-resistance state, Schottky emission and Frenkel-Poole emission are fitted. In addition, after HTF treatment, the resistance of conductive filament decreases. The different high-resistance-state characteristics in the two devices can be attributed to more oxygen ions generated by the serious damage during HTF. Finally, the switching behavior activated by low-temperature forming process is employed to confirm the model.

Reset Current Reduction with Excellent Filament Controllability by Using Area Minimized and Field Enhanced Unipolar Resistive Random Access Memory Structure

We firstly propose a novel resistive random access memory (RRAM) cell structure, which makes it possible to minimize the switching area and to maximize the electrical field where resistive switching occurs, resulting in the improvement of resistive switching characteristics. With excellent structural advantages, resistive switching characteristics such as reset current and set voltage fluctuation are improved through the enhancement of conductive filament (CF) controllability. A simple fabrication process is delivered and the device performance from the viewpoints of the forming voltage, set voltage, and reset current is investigated. Conducting defect effects are also investigated in comparison with the conventional RRAM cell structure. Numerical simulation is performed using a random circuit breaker (RCB) model to confirm the proposed structure.

Effects of Conductive Defects on Unipolar RRAM for the Improvement of Resistive Switching Characteristics

Effects of Conductive Defects on Unipolar RRAM for the Improvement of Resistive Switching Characteristics

Improvement of resistive switching characteristics in TiO2 thin films with embedded Pt nanocrystals

We have fabricated TiO2 thin films with embedded Pt nanocrystals (Pt-NCs) and investigated the resistive switching characteristics for nonvolatile memory application. Reversible and steady bistable resistance switching behavior was observed for the Pt/TiO2/Pt capacitors with Pt-NCs embedded in the TiO2 films. Moreover, an improvement in the stability of resistance switching and retention properties was also achieved from the embedding of uniform and fine Pt-NCs.

Improvement of Resistive Switching Characteristics in $\hbox{SrZrO}_{3}$ Thin Films With Embedded Cr Layer

The stabilization of the resistive switching properties is necessary to realize the memory application of the SrZrO3(SZO)-based resistive switching devices. During continuous resistive switching cycle, broad variations of the resistive switching parameters of the SZO-based memory devices can be improved by a thin embedded Cr layer. The Cr metal layer is proposed to diffuse into and dope the SZO thin film to produce the space charge region, further reducing the effective resistive switching region. Hence, the good stabilization of the resistive switching properties can be obtained in the SZO films with embedded Cr layer.