Woven resistive switching using aluminum and carbon fibers for memory devices

이미정 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Recently, wearable electronics such as google glasses and smart watch were launched in the market to recieve increasing attention as new generation electronic devices. In the near future, wearable electronics will be literally‘wearable’as smart clothing, smart fabrics and electronic textile form. Some researchers reported electronic textiles suitable for integration of devices using metal wire or conductive yarn. In this paper, we fabricated resistive switching memory devices using one dimensional conductive yarn for flexible electronic textile based on solution processes. Conducting fibers costructing texture were fabricated using and Al coated on carbon yarn, which act as an electrode. Carbon yarns, core of fiberes, were exposed to catalyst and immersed in alumi num precursor solution. Then Polymethylmethacrylate (PMMA) is coated on the conductive aluminium yarn using dip coating method to prevent a short between condcuting fibers and to act as a resistive switching layer. Carbon yarn was placed on the PMMA/Al coated yarn perpendiculary to form another electrode. We observed resistive switching characteristics of Carbon/PMMA/Al/Carbon fiber cross structure. Without forming process, the devices show bipolar resistive switching. The virgin device is in low resistance state. When positive bias is applied, the device switches to high resistance state. In this manner, ‘write’ and ‘erase’ operation was possible switch the resistance of the junction devices of two fibers. Interesting thing is the switching of resistivity worked even more stably without insulating PMMA layer. The device performed with switching more than 100 cycles endurance and retention properties up to 10000s only with two conducting fibers crossed. According to EDS and SEM results, we contemplate that resistive switching occurs in the Al layer which containes significant oxygen level to show native oxide layer of aluminum involved in the process. Furthermore, XPS analysis showed that new phase could be the main reason for the unique properties of resistive switching with two conducting layers which was not observed in conventional metal/metal structure. Switching mechanism with aluminum/carbon structure could be explained in this work with various analysis at the interface and by exploring different configuration of the device structure. Although the study is in early stage, this result shows the possibility of simple approach towards woven electronics using only flexible conductive yarns working with novel mechanism.

Direct Observation of Domain Motion Synchronized with Resistive Switching in Multiferroic Thin Films

Lee, Ji Hye,Yoon, Chansoo,Lee, Sangik,Kim, Young Heon,Park, Bae Ho American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.51

<P>The room-temperature resistive switching characteristics of ferroelectric, ferroelastic, and multiferroic materials are promising for application in nonvolatile memory devices. These resistive switching characteristics can be accompanied by a change in the ferroic order parameters via applied external electric and magnetic excitations. However, the dynamic evolution of the order parameters between two electrodes, which is synchronized with resistive switching, has rarely been investigated. In this study, for the first time, we directly monitor the ferroelectric/ferroelastic domain switching dynamics between two electrodes in multiferroic BiFeO3 (BFO) planar devices, which cause resistive switching, using piezoresponse force microscopy. It is demonstrated that the geometrical relationship between the ferroelectric domain and electrode in BFO planar capacitors with only 71 domain walls significantly affects both the ferroelectric domain dynamics and the resistive switching. The direct observation of domain dynamics relevant to resistive switching in planar devices may pave the way to a controllable combination of ferroelectric characteristics and resistive switching in multiferroic materials.</P>

Effect of AlN layer on the resistive switching properties of TiO2 based ReRAM memory devices

Bhawani Pratap Singh Rathore,Ravi Prakash,Davinder Kaur 한국물리학회 2018 Current Applied Physics Vol.18 No.1

The present study reports the resistive switching behaviour in Titanium Dioxide (TiO2) material, with possible implementations in non volatile memory device. The Cu/TiO2/Pt memory device exhibit uniform and stable bipolar resistive switching behaviour. The current-voltage (I-V) analysis shows two discrete resistance states, the High Resistance State (HRS) and the Low Resistance State (LRS). The effect of an additional AlN layer in the resistive memory cell is also investigated. The Cu/TiO2/AlN/Pt device shows a multilevel (tri-state) resistive switching. Multilevel switching is facilitated by ionic and metallic filament formation, and the nature of the formed filaments is confirmed by performing a resistance vs. temperature measurement. The bilayer device shows improved reliability over the single layer device. The formation of high thermal conductive interfacial oxy-nitride (AlON) layer is the main reasons for the enhancement of resistive switching properties in Cu/TiO2/AlN/Pt cell. The performance of device was measured in terms of endurance and retention, which exhibits good endurance over 105 cycles and long retention time of 105 s at 125 C. The above result suggests the feasibility of Cu/TiO2/AlN/Pt devices for multilevel non volatile ReRAM application.

Electroforming-less and multi-level resistive switching characteristics in tungsten oxide thin film

Lee, Seunghyup,Yun, Ki Hoon,Kim, Doeun Elsevier 2019 THIN SOLID FILMS - Vol.674 No.-

<P><B>Abstract</B></P> <P>Thermally grown tungsten oxide (WOx) thin film on a tungsten electrode is studied as a potential memristor material. Due to the dislocation formation inside the film, the device could present stable memristive characteristics without electroforming process. In this research, the opportunity of applying the WOx memristor to the multi-level resistive switching behavior based multi-level memory or artificial synaptic device was presented. In particular, the flexibility of the device shows the possibility of a future flexible memory device. Interpreting the memristive characteristics, the resistance switching mechanism was discussed based on the valance change at the device structure interface. Based on the simple fabrication process and electroforming-less operation, the results present the possibility of applying WOx based memristors in current electronic devices at an early stage. This work reveals a useful proposal of WOx based memristors for emerging device applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Memristive characteristics studies of thermally grown tungsten oxide thin film. </LI> <LI> Investigation of electroforming-less, multi-level resistive switching. </LI> <LI> Flexible memristive characteristics of tungsten oxide thin film device. </LI> <LI> Interpretation of interfacial valance change based resistive switching behavior. </LI> </UL> </P>

Prediction of the Current-Voltage Characteristics and the Bipolar Resistive Switching Mechanism in Polymer-Based Sandwiched Structures

Muhammad Naeem Awais,Muhammad Naeem Shehzad 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.5

The prediction of the current-voltage (IV) characteristics of resistive switching devices has remained a challenge before their physical realization. This research work addresses the prediction of the IV characteristics and the bipolar switching mechanism of polymer-based resistive switches by examining their structures before their fabrication. The research was carried out through an analytical study of the device structure, thereby correlating the predicted IV curve to the \textit{in-situ} IV characteristics of the device. Different types of the device structures were considered, depending upon the work function of the top and the bottom electrodes and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of the sandwiched layer. We concluded that the defects/traps within the sandwiched layer lead to the interface effect being the dominant switching mechanism driving the polymer-based resistive switches. Furthermore, we also found that the devices following the interface effect are driven from trap-limited space-charge-limited current (SCLC) conduction to trap-free SCLC conduction as their current conduction mechanisms.

Unipolar Resistive Switching of EuxOy Polycrystalline Films

박배호,김상훈,최진식,이장원,JaeGwan Chung,서선애 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2

Polycrystallized EuxOy thin films show unipolar resistive switching. The ratios of the resistance values of the high-resistance state to those of the low-resistance state are as large as 108. The deposited EuxOy thin films show mixed phases, Eu2O3 and Eu3O4. The relative concentration of the phases could be controlled by using the oxygen gas flow rate during growth. A high oxygen concentration leads to broadening the distribution of the switching voltages, inducing transitions between the high-resistance state and the low-resistance state. We observe that the distribution of the switching voltage from the high-resistance state to the low-resistance state (VSET ) is smaller than or comparable to that of the switching voltage inducing the opposite transition (VRESET ) in well-controlled EuxOy thin films.

Thickness-dependent Resistance Switching in Cr-doped SrTiO3

김태광,두혜원,김민창,서순애,황인록,김연수,Jihoon Jeon,Sangik Lee,박배호 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.5

Thickness dependent bipolar resistance switching behavior was investigated on epitaxially grown Cr-doped SrTiO<SUB>3</SUB> (Cr-STO). All the pristine devices of different thickness show polarity independent symmetric current-voltage characteristic and the same space charge limited conduction mechanism. However, after a forming process the resultant conduction and switching phenomena are significantly disparate depending on the thickness of Cr-STO. The forming process itself is highly influenced by resistance values of each pristine device. Based on our results, we suggest that the resistance switching mechanism in Cr-STO is dependent not only on the insulating material composition or contact metal as previously reported but also on the initial resistance level determined by geometry and the quality of the insulating material. Bipolar resistance switching behavior in oxide material of different thickness exhibit mixed bulk and interface switching. This indicates that efforts in resistance based memory research should be focused on scalability or process method to control a given oxide material in addition to material type and device structure.

Stacked resistive switches for AND/OR logic gates

Kim, M.J.,Son, K.R.,Park, J.H.,Kim, T.G. Pergamon Press ; Elsevier Science Ltd 2017 Solid-state electronics Vol.132 No.-

This paper reports the use of stacked resistive switches as logic gates for implementing the ''AND'' and ''OR'' operations. These stacked resistive switches consist of two resistive switches that share a middle electrode, and they operate based on the difference in resistance between the low and high resistance states indicating the logical states of ''0'' and ''1'', respectively. The stacked resistive switches can perform either AND or OR operation, using two read schemes in one device. To perform the AND (or OR) operation, two resistive switches are arranged in a serial (or parallel) connection. AND and OR operations have been successfully demonstrated using the stacked resistive switches. The use of stacked resistive switches as logic gates that utilize the advantages of memristive devices shows the possibility of stateful logic circuits.

2P-139 Resistive analog switching in Au/La₂O₃/Pt structure

강원규,정헌상,김두진,나현빈,이현호 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

Analog-type resistive switching with sequentially changing resistance has attracted interest recently for applications such as analog nonvolatile memory, programmable analog circuits, and neuromorphic devices. Nanomaterials such as nanoparticles (NPs) films have been demonstrated to exhibit digital nonvolatile resistive switching and analog switching. The usage of nanoparticles has the advantage that the internal structure can be designed during the synthesis stage to assemble a stacked 2D plate structure. In this study, characteristics of square-shaped 2D La₂O₃ nanoparticles layer between Au and Pt electrodes were investigated. The current-voltage curves show hysteresis with decreasing resistance for repeating negative voltage sweeps and increasing resistance for repeating positive-voltage sweeps. furthermore, the analog switching with respect to the polarity of voltage is equivalent to adaptive synaptic motion of potentiation and depression of biological system.

Coexistence of nonvolatile unipolar and volatile threshold resistive switching in the Pt/LaMnO3/Pt heterostructures

Yin Yanfeng,Kang Chaoyang,Jia Caihong,Zhang Weifeng 한국물리학회 2021 Current Applied Physics Vol.31 No.-

Coexistence of nonvolatile unipolar and volatile threshold resistive switching is observed in the Pt/LaMnO3 (LMO)/Pt heterostructures. The nonvolatile unipolar memory is achieved by applying a negative bias, while the volatile threshold resistive switching is obtained under a positive bias. Additionally, the pristine low resistance state (LRS) could be switched to high resistance state (HRS) by the positive voltage sweeping, which is attributed to the conduction mechanism of Schottky emission. Subsequently, the insulator-to-metal transition in the LMO film due to formation of ferromagnetic metallic phase domain contributes to the volatile threshold resistive switching. However, the nonvolatile unipolar switching under the negative bias is ascribed to the formation/ rupture of oxygen-vacancy conducting filaments. The simultaneously controllable transition between nonvolatile and volatile resistance switching by the polarity of the applied voltage exhibits great significance in the applications of in-memory computing technology.