scholarly journals Voltage Amplitude-Controlled Synaptic Plasticity from Complementary Resistive Switching in Alloying HfOx with AlOx-Based RRAM

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1410 ◽  
Author(s):  
Hojeong Ryu ◽  
Junhyeok Choi ◽  
Sungjun Kim
Keyword(s):  
Synaptic Plasticity ◽  
Resistive Switching ◽  
Photoelectron Spectroscopy ◽  
Differential Resistance ◽  
Memory Device ◽  
Spike Timing ◽  
Voltage Amplitude ◽  
Forming Process ◽  
Voltage Sweep ◽  
Current Sweep

In this work, the synaptic plasticity from complementary resistive switching in a HfAlOx-based resistive memory device was emulated by a direct current (DC) voltage sweep, current sweep, and pulse transient. The alloyed HfAlOx dielectric was confirmed by X-ray photoelectron spectroscopy analysis. The negative differential resistance observed before the forming and set processes can be used for interface resistive switching with a low current level. Complementary resistive switching is obtained after the forming process at a negative bias. This unique resistive switching is also suitable for synaptic device applications in which the reset process occurs after an additional set process. The current sweep mode provides more clear information on the complementary resistive switching. Multiple current states are achieved by controlling the amplitude of the set and reset voltages under DC sweep mode. The potentiation and depression characteristics are mimicked by varying the pulse voltage amplitude for synaptic device application in a neuromorphic system. Finally, we demonstrate spike-timing-dependent plasticity by tuning the timing differences between pre-spikes and post-spikes.

scholarly journals Synaptic Characteristics from Homogeneous Resistive Switching in Pt/Al2O3/TiN Stack

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2055 ◽  
Author(s):  
Hojeong Ryu ◽  
Sungjun Kim
Keyword(s):  
Resistive Switching ◽  
High Resistance ◽  
Differential Resistance ◽  
Forming Process ◽  
Short Term Plasticity ◽  
Low Resistance ◽  
Current Decay ◽  
Operation Conditions ◽  
Setting Process ◽  
Negative Differential Resistance Effect

In this work, we propose three types of resistive switching behaviors by controlling operation conditions. We confirmed well-known filamentary switching in Al2O3-based resistive switching memory using the conventional device working operation with a forming process. Here, filamentary switching can be classified into two types depending on the compliance current. On top of that, the homogeneous switching is obtained by using a negative differential resistance effect before the forming or setting process in a negative bias. The variations of the low-resistance and high-resistance states in the homogeneous switching are comparable to the filamentary switching cases. However, the drift characteristics of the low-resistance and high-resistance states in the homogeneous switching are unstable with time. Therefore, the short-term plasticity effects, such as the current decay in repeated pulses and paired pulses facilitation, are demonstrated when using the resistance drift characteristics. Finally, the conductance can be increased and decreased by 50 consecutive potentiation pulses and 50 consecutive depression pulses, respectively. The linear conductance update in homogeneous switching is achieved compared to the filamentary switching, which ensures the high pattern-recognition accuracy.

scholarly journals Comparison of diverse resistive switching characteristics and demonstration of transitions among them in Al-incorporated HfO2-based resistive switching memory for neuromorphic applications

RSC Advances ◽  
2020 ◽  
Vol 10 (52) ◽  
pp. 31342-31347
Author(s):  
Sobia Ali Khan ◽  
Sungjun Kim
Keyword(s):  
Resistive Switching ◽  
Memory Device ◽  
Voltage Amplitude ◽  
Resistive Switching Memory ◽  
Sweep Voltage ◽  
Switching Characteristics ◽  
Switching Memory

Diverse resistive switching behaviors are observed in the Pt/HfAlOx/TiN memory device depending on the compliance current, the sweep voltage amplitude, and the bias polarity.

scholarly journals Bipolar and Complementary Resistive Switching Characteristics and Neuromorphic System Simulation in a Pt/ZnO/TiN Synaptic Device

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 315 ◽  
Author(s):  
Sobia Ali Khan ◽  
Geun Ho Lee ◽  
Chandreswar Mahata ◽  
Muhammad Ismail ◽  
Hyungjin Kim ◽  
...  
Keyword(s):  
Resistive Switching ◽  
Photoelectron Spectroscopy ◽  
Recognition Rate ◽  
Long Term Potentiation ◽  
Memory Device ◽  
Chemical Information ◽  
Bipolar Resistive Switching ◽  
Cross Point ◽  
Pulse Input

In this work, a ZnO-based resistive switching memory device is characterized by using simplified electrical conduction models. The conventional bipolar resistive switching and complementary resistive switching modes are accomplished by tuning the bias voltage condition. The material and chemical information of the device stack including the interfacial layer of TiON is well confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The device exhibits uniform gradual bipolar resistive switching (BRS) with good endurance and self-compliance characteristics. Moreover, complementary resistive switching (CRS) is achieved by applying the compliance current at negative bias and increasing the voltage at positive bias. The synaptic behaviors such as long-term potentiation and long-term depression are emulated by applying consecutive pulse input to the device. The CRS mode has a higher array size in the cross-point array structure than the BRS mode due to more nonlinear I–V characteristics in the CRS mode. However, we reveal that the BRS mode shows a better pattern recognition rate than the CRS mode due to more uniform conductance update.

A resistive switching memory device with a negative differential resistance at room temperature

2018 ◽  
Vol 113 (5) ◽  
pp. 053502 ◽  
Author(s):  
Mayameen S. Kadhim ◽  
Feng Yang ◽  
Bai Sun ◽  
Yushu Wang ◽  
Tao Guo ◽  
...  
Keyword(s):  
Resistive Switching ◽  
Negative Differential Resistance ◽  
Room Temperature ◽  
Differential Resistance ◽  
Memory Device ◽  
Resistive Switching Memory ◽  
Switching Memory

scholarly journals Demonstration of Threshold Switching and Bipolar Resistive Switching in Ag/SnOx/TiN Memory Device

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1605
Author(s):  
Jooyoung Pyo ◽  
Seungjin Woo ◽  
Kisong Lee ◽  
Sungjun Kim
Keyword(s):  
Resistive Switching ◽  
Photoelectron Spectroscopy ◽  
Pulse Amplitude ◽  
Memory Device ◽  
Gradual Transition ◽  
Bipolar Resistive Switching ◽  
Memory Switching ◽  
Threshold Switching ◽  
Non Volatile Memory ◽  
Multiple Pulses

In this work, we observed the duality of threshold switching and non-volatile memory switching of Ag/SnOx/TiN memory devices by controlling the compliance current (CC) or pulse amplitude. The insulator thickness and chemical analysis of the device stack were confirmed by transmission electron microscope (TEM) images of the Ag/SnOx/TiN stack and X-ray photoelectron spectroscopy (XPS) of the SnOx film. The threshold switching was achieved at low CC (50 μA), showing volatile resistive switching. Optimal CC (5 mA) for bipolar resistive switching conditions with a gradual transition was also found. An unstable low-resistance state (LRS) and negative-set behavior were observed at CCs of 1 mA and 30 mA, respectively. We also demonstrated the pulse operation for volatile switching, set, reset processes, and negative-set behaviors by controlling pulse amplitude and polarity. Finally, the potentiation and depression characteristics were mimicked by multiple pulses, and MNIST pattern recognition was calculated using a neural network, including the conductance update for a hardware-based neuromorphic system.

scholarly journals Conductance Quantization Behavior in Pt/SiN/TaN RRAM Device for Multilevel Cell

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1918
Author(s):  
Jongmin Park ◽  
Seungwook Lee ◽  
Kisong Lee ◽  
Sungjun Kim
Keyword(s):  
Resistive Switching ◽  
Photoelectron Spectroscopy ◽  
Pulse Train ◽  
Conduction Mechanism ◽  
Differential Resistance ◽  
X Ray ◽  
Conductance Quantization ◽  
Negative Differential Resistance Effect ◽  
Memristor Device ◽  
Sweep Speed

In this work, we fabricated a Pt/SiN/TaN memristor device and characterized its resistive switching by controlling the compliance current and switching polarity. The chemical and material properties of SiN and TaN were investigated by X-ray photoelectron spectroscopy. Compared with the case of a high compliance current (5 mA), the resistive switching was more gradual in the set and reset processes when a low compliance current (1 mA) was applied by DC sweep and pulse train. In particular, low-power resistive switching was demonstrated in the first reset process, and was achieved by employing the negative differential resistance effect. Furthermore, conductance quantization was observed in the reset process upon decreasing the DC sweep speed. These results have the potential for multilevel cell (MLC) operation. Additionally, the conduction mechanism of the memristor device was investigated by I-V fitting.

scholarly journals Investigation of memory effect in Au/(Ti-Cu)Ox-gradient thin film/TiAlV structure

2021 ◽  
Author(s):  
Damian Wojcieszak ◽  
Jarosław Domaradzki ◽  
Michał Mazur ◽  
Tomasz Kotwica ◽  
Danuta Kaczmarek
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Resistive Switching ◽  
Photoelectron Spectroscopy ◽  
Electrical Contacts ◽  
Switching Behavior ◽  
Oxide Thin Film ◽  
Electrical Measurements ◽  
Forming Process ◽  
Gradient Distribution

The paper presents the results of the analysis of resistive switching properties observed in (Ti-Cu)-oxide thin film with gradient distribution of elements over the thin film thickness. Thin films were prepared using the multisource reactive magnetron co-sputtering process. Programmed profile of the pulse width modulation coefficient during sputtering of the Cu target allowed to obtain the designed gradient U-shape profile of Cu concentration in the deposited thin film. Electrical measurements of Au/(Ti-Cu)Ox/TiAlV structure showed the presence of nonpinched hysteresis loops in the voltage–current plane testifying the resistive switching behavior. Additionally, the initial forming process of conducting filaments has been observed as well. Optical, x-ray, and ultraviolet photoelectron spectroscopy measurements allowed to create the scheme of the bandgap alignment of the prepared thin films with respect to the Au and TiAlV electrical contacts. Detailed structure and elemental profile investigations allowed to conclude about the presence of conducting filaments of the observed resistive switching mechanism occurring in the prepared test structure. The obtained results showed that the prepared gradient (Ti-Cu)Ox thin film could be an interesting alternative to the conventional multilayer stack construction of resistive switching devices.

Bottom Electrode Properties and Electrical Field Cycling Effects on HfOx based Resistive Switching Memory Device

2020 ◽  
Author(s):  
J. Li ◽  
Y. Kim ◽  
D. Kong ◽  
K. Cheng ◽  
S. -C. Seo ◽  
...  
Keyword(s):  
Resistive Switching ◽  
Bottom Electrode ◽  
Driving Forces ◽  
Rapid Development ◽  
Memory Device ◽  
Forming Process ◽  
Resistive Switching Memory ◽  
Voltage Bias ◽  
Before And After ◽  
Switching Memory

Abstract The continuously growing demands in high-density memories drive the rapid development of advanced memory technologies. In this work, we investigate the HfOx-based resistive switching memory (ReRAM) stack structure at nanoscale by high resolution TEM (HRTEM) and energy dispersive X-ray spectroscopy (EDX) before and after the forming process. Two identical ReRAM devices under different electrical test conditions are investigated. For the ReRAM device tested under a regular voltage bias, material redistribution and better bottom electrode contact are observed. In contrast, for the ReRAM device tested under an opposite voltage bias, different microstructure change occurs. Finite element simulations are performed to study the temperature distributions of the ReRAM cell with filaments formed at various locations relative to the bottom electrode. The applied electric field as well as the thermal heat are the driving forces for the microstructure and chemical modifications of the bottom electrode in ReRAM deceives.

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