Ultra-Low Power Consumption Flexible Biomemristors - ACS Applied

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Ultra-Low Power Consumption Flexible Biomemristors Min-Kyu Kim, and Jang-Sik Lee ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b01781 • Publication Date (Web): 21 Feb 2018 Downloaded from http://pubs.acs.org on February 25, 2018

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Ultra-Low Power Consumption Flexible Biomemristors Min-Kyu Kim and Jang-Sik Lee*

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea

KEYWORDS: Biomemristors, resistive switching, carboxymethyl carrageenan, flexible electronics, low power consumption

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ABSTRACT

Low power consumption is the important requirement in memory devices for saving energy. In particular, improved energy-efficiency is essential in implantable electronic devices for operation under a limited power supply. Here, we demonstrate the use of κ-carrageenan (κ-car) as the resistive switching layer to achieve memory that has low power consumption. A carboxymethyl (CM) group is introduced to the κ-car to increase its ionic conductivity. Ag was doped in CM:κcar to improve the resistive switching properties of the devices. Memory devices based on Agdoped CM:κ-car showed electroforming-free resistive switching. This device exhibited low reset voltage (~ 0.05 V), fast switching speed (50 ns), and high ON/OFF ratio (> 103) under low compliance current (10-5 A). Its power consumption (~0.35 µW) is much lower than those of previously-reported biomemristors. The resistive switching may be a result of an electrochemical redox process and Ag filament formation in the CM:κ-car under an electric field. This biopolymer memory can also be fabricated on flexible substrate. This study verifies the feasibility of using biopolymers for applications to future implantable and biocompatible nanoelectronics.

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1. INTRODUCTION Redox-based resistive switching random access memory (ReRAM) has low power consumption, fast switching speed, simple device structure, and high scalability, and is therefore a promising form of next-generation nonvolatile memory.1 Many materials can be used for resistive switching layers; examples include inorganics, organics, and hybrid materials.2-7 Organic materials have been evaluated for these uses because they are flexible, printable, transparent, and compatible with diverse substrates.8-11 ReRAMs based on biopolymers have been developed because they are abundant in nature, renewable, biodegradable, biocompatible, and inexpensive. Various biopolymers based on proteins or polysaccharides have shown potential for use as resistive switching layers.12-25 These materials are biocompatible, so ReRAMs based on biopolymers can be used as implantable devices, but they have high operating current and voltage, whereas low power consumption is an important requirement for implantable biomedical instrumentation.26-27 One way to achieve biodegradable ReRAM with low power consumption is to use a metal-doped biodegradable natural material.24 κ-carrageenan (κ-car) is a linear-sulfated polysaccharide in seaweeds.28 This polymer has been considered as a promising and environmentally-benign alternative to petroleum-based polymers.29-33 Modification of κ-car by substitution of a carboxymethyl (CM) group in the biopolymer molecules34-35 increases the number of oxygen atoms and therefore yields more vacancies and higher ionic conductivity than in the parent κ-car,33 while not affecting its biodegradability. Therefore, this modification can be exploited to functionalize the biopolymer to improve its desirable properties. Because of the improved properties of CM:κ-car, it has been investigated for use in fuel cells, sensors, batteries and solar cells,29-32, 36 but to our knowledge, it has never been studied for application in memory devices.

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This study introduces CM:κ-car for use in nonvolatile biopolymer memory. ReRAM based on CM:κ-car was fabricated by solution process and its electrical characteristics were investigated. The properties of κ-car are improved by carboxymethylation and the electrical characteristic is controlled by Ag doping. Ag+ ions generated by doping in a polysaccharide matrix enhance the formation of metal filaments. Therefore, Ag-doped CM:κ-car devices can be operated under low compliance current (CC). Also, this device exhibits long data retention and fast switching. This paper shows the feasibility of using CM:κ-car to fabricate implantable and biodegradable memory devices that consume little power.

2. RESULT AND DISCUSSION The CM functional group contains oxygen. Therefore the introduction of the CM functional group to κ-car may increase the number of sites at which cations can coordinate. This increase in the number of functionality in CM:κ-car can lead to increase in ionic conductivity.31-33 The ionic conductivity is one of the most important factors in filament formation.37-38 The undoped CM:κcar and κ-car devices had different electrical characteristics. Ag/ κ-car/ Pt devices formed unstable filaments even under high CC = 10-4 A, but Ag/ CM:κ-car / Pt can exhibited resistive switching behavior under the same CC (Figure S1). The different ionic conductivity seems to be the reason for this difference in resistive switching characteristics. So we used CM:κ-car as the resistive switching active layer to enhance filament formation in the biopolymer, i.e., an Ag (top electrode)/ CM:κ-car / Pt (bottom electrode) structure was used to demonstrate the resistive switching property (Figure 1a). The electrical characteristics of CM:κ-car can be controlled by Ag doping. Undoped CM:κ-car exhibits unidirectional threshold switching under low CC = 10-5 A. Electrical properties of Ag/

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CM:κ-car /Pt were measured under dc voltage sweep (0 V  0.5 V  0 V  - 0.5 V). The devices in initial resistance state had low off-current (~10-9 A), and the current changed abruptly to 10-5 A at 0.3 V. When the voltage sweep reached a 0.1 V during the backward sweep, the current through the devices decreased to the initial low off-current level. However, threshold resistive switching behavior was not observed during the negative voltage sweep. This unidirectional threshold resistive switching characteristics can be understood as Ag filament formation by the active Ag top electrode and the spontaneous rupturing of the unstable Ag filament.25, 39-41 In undoped CM:κ-car, the filaments initiated only from one side of the Ag top electrode, so devices can be operated only under positive voltage sweep.42 This limited filament source can lead to unstable filament formation, because the Ag top electrode is insufficient for stable filament formation under low CC. Therefore we used Ag doping to form stable filament under low CC. Ag-doped CM:κ-car exhibits nonvolatile resistive switching under low CC = 10-5 A (Figure 1b). During positive voltage sweep from 0 V to +0.3 V, the current increased abruptly at ~+0.2 V; i.e., the device state switched from high-resistance state (HRS, OFF state) to low-resistance state (LRS, ON state). Spontaneous filament rapturing did not occur in Ag-doped CM:κ-car devices. By applying negative voltage sweep from 0 V to -0.2 V, the current decreased rapidly at ~ -0.07 V; i.e., the device state changed from LRS to HRS. The resistive switching characteristics of Ag-doped CM:κ-car devices were investigated. I-V curves were obtained from 20 devices (Figure 2a). The Ag-doped CM:κ-car devices exhibited bipolar resistive switching under low CC (10-5 A) without electroforming process. The device-todevice uniformity was measured with 20 samples. There was a slight fluctuation in HRS and LRS current levels, but overall higher than 103 on/off ratio was maintained (Figure 2b). To estimate the electrical reliability of these Ag-doped CM:κ-car devices, the retention properties of

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both HRS and LRS were measured by applying a reading bias of +0.02 V. The current fluctuated slightly during the HRS, but the ON/OFF ratio was maintained for > 104 s (Figure 2c). The resistive switching memory devices based on Ag-doped CM:κ-car respond quickly to applied set voltage pulse (Figure 2d). Before applying the pulse, device state was confirmed by dc voltage bias sweep (0 to +0.03 V). Set and reset processes do not occur in this voltage range, so the bias sweep did not cause resistive switching. After applying a pulse generated by a waveform generator, a dc voltage bias sweep was performed to determine whether the resistance of devices had changed. A set voltage pulse (+0.4 V, 50 ns) was used to switch the device resistance state (Figure 2d: inset). The 50-ns pulse was enough to switch the resistance states of the devices. Devices in LRS can be switched to HRS by applying a reset voltage pulse (-0.4 V, 50 ns). To compare low-power-consumption properties of resistive switching memory devices based on CM:κ-car, we plotted the reset voltage versus the reset current of bio-ReRAM devices (Figure 3a). Proteins such as gelatin, fibroin and albumen are the most-widely studied bio-materials for resistive switching; they show varied reset voltage and relatively high reset current (> 10-3 A).1220

Polysaccharides such as chitosan, starch, and cellulose, demonstrate the lowest reset current

with relatively low reset voltage.21-22, 24 Among bio-ReRAMs, the CM:κ-car devices have the lowest reset current (7.82×10-6 A) and reset voltage (- 0.045 V), so their power consumption is < 0.35 µW (Figure 3b). This value is orders of magnitude lower than those of polysaccharidebased ReRAMs. In addition, the power consumption based on the pulse mode was calculated. When set pulse (50 ns, 0.4 V) and reset pulse (50 ns, -0.4 V) used for pulse operation, the energy of only ~200 fJ is necessary for switching the device. One application of bio-ReRAM is as biocompatible electronic devices, so low power consumption is an important requirement.

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Therefore, this result shows that ReRAM based on Ag-doped CM:κ-car has great potential as biocompatible and implantable memory device. The switching and conduction mechanism in the Ag-doped CM:κ-car memory device was investigated by the I-V curve of memory device plotted as log I-log V at the positive and negative voltage sweep region (Figure S2). The fitted result of LRS and HRS current indicate that space-charge-limited conduction (SCLC) is dominant conduction mechanism for HRS and Ohmic conduction is dominant mechanism for LRS. The two distinguishable section was observed in the fitted I-V curve of the HRS region; the low voltage region was linear (I ~V), whereas the high voltage region showed quadratic behavior (I ~V2) before the set process. The traps due to defects of switching layer is believed to the reason of these behavior. When the applied bias is low, there are a lot of thermally generated free charge carriers compared to injected carrier, which shows Ohmic conduction. When the applied bias is increased, the sufficient electric field to fill all trap centers is applied, injected carriers are dominant for conduction until set process. In contrast, Ohmic conduction was only observed in the fitted curve of the LRS region. It indicates a filamentary switching mechanism by Ag conductive path formed between two electrodes.43 The resistive switching behavior may be a result of the formation of Ag filaments within the CM:κ-car matrix. Our device consists of an active Ag top electrode and an inert Pt bottom electrode. Ag contributes to formation of metal filaments in electrochemical metallization cells.44 The hypothesis is as follows (Figure 4). The Ag/undoped CM:κ-car /Pt device has no Ag+ ions in its pristine state (Figure 4a). When positive voltage is applied to the Ag top electrode, oxidation at the interface between CM:κ-car and Ag electrode can generate Ag+ ions; they migrate toward the Pt cathode. As a result, Ag filaments form across the CM:κ-car layer by reduction of Ag+,

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and the device switches from HRS to LRS (Figure 4b).8, 43, 45-46 However, these filaments rupture during the backward sweep in Ag/undoped CM:κ-car/Pt devices (Figure 4c), because under low CC = 10-5 A, the number of Ag+ ions released by the Ag top electrode is limited, so only weak filaments form.47 Weak filaments dissolve easily after the voltage is removed. For Ag filaments, this effect has been described thermodynamically as a competition between the surface and volume energies.39-41 To suppress this behavior, the thickness of the filaments must be increased. In the Ag/Ag-doped CM:κ-car/Pt device, the extra Ag source to thicken filaments is provided by Ag doping (Figure 4d). When a positive voltage is applied to the Ag top electrode, both Ag+ ions oxidized from Ag top electrode and pre-existing Ag+ ions in Ag-doped CM:κ-car can contribute to filament formation, i.e; pre-existing Ag+ ions can support stable filament formation (Figure 4e).48 Also, Ag-doping can enhance ionic conductivity and oxidation rate which have critical effect on filament formation process.31,

37, 48

In addition, pre-existing Ag+ ions can make

preferential paths of filament and support uniform filament formation.24 The resulting thick and stable filaments do not dissipate after the voltage is removed, so the LRS can be maintained. To change the device to HRS, a negative voltage should be applied to rupture the thick filaments. Therefore, the filament can be ruptured by Joule heating and the presence of an electric field (Figure 4f). Devices can only be operated in bipolar mode because breakdown occurred during the unipolar reset process (Figure S3). When a negative voltage is applied to top electrode for reset process, Joule heating and Ag+ ions migration toward top electrode can occur simultaneously. In this case, the regrowth of Ag filament can be suppressed during the reset process because there are no Ag source in the inert Pt bottom electrode. However, when positive voltage is applied to top electrode for reset process, the regrowth of Ag filament or breakdown of

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device can occur because Ag ions can migrate toward bottom electrode from Ag top electrode of residual filament. So, reproducible resistive switching behavior is only observed in bipolar mode. As a memory device, flexibility is a highly-desired characteristic that would allow next generation of nanoelectronics to be used in wearable, biocompatible and implantable electronics.4, 18, 21, 49 Organic materials have been considered as good candidates and investigated for flexible memory devices.13,

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Therefore, the feasibility of Ag-doped CM:κ-car for the

flexible resistive switching memory devices was demonstrated. ReRAM devices with Ag/CM:κcar/Pt structure were fabricated on flexible polyethylene terephthalate substrates (Insets of figure 5). Device structure and fabrication method were identical with those of devices fabricated on silicon substrates. Under tensile and compressive stresses with 15 mm radius of curvature, devices fabricated on flexible substrates showed similar I-V characteristics to those of devices on flat substrates (Figure 5). The reproducibility of resistive switching behavior under tensile and compressive stresses was also confirmed for over 50 dc cycles (Figure S4).

3. CONCLUSION We demonstrated biomaterial-based ReRAM using solution-processed CM:κ-car. Use of CM to chemically modify κ-car increased its ionic conductivity and the stability of its resistive switching behavior. To enhance filament formation, Ag ions were doped into the CM:κ-car matrix. ReRAM devices based on Ag-doped CM:κ-car exhibited electroforming-free resistive switching with fast switching speed and low set and reset voltages under low CC (10-5 A). This operation under low CC facilitated low power consumption. The resistive switching mechanism may be a result of an electrochemical redox process, which forms Ag filaments in the biopolymer layer. In addition, the feasibility of CM:κ-car-based flexible devices was

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demonstrated. We believe that such devices are promising as implantable and biocompatible nanoelectronics on flexible substrates.

4. EXPERIMENTAL SECTION 4.1 Materials and Device preparation. CM:κ-car powder was prepared according to the method reported by previous papers.34-35 5 g of κ-car (sulfated plant polysaccharide, Sigma-Aldrich, CAS number: 11114-20-8) powder was suspended in 100 ml isopropyl alcohol at room temperature. After that, 8 ml of sodium hydroxide solution was added. 18.1g of monochloroacetic acid (≥99.0%, Sigma-Aldrich, CAS number: 78-11-8) was added, and the mixture was heated to 50 °C for 4 h with continuous stirring. The reaction product was recovered by vacuum filtration and washed three times with 50 ml ethanol-water (4:1) and ethanol wash alternation. The resulting CM:κ-car was oven-dried at 70 °C overnight. The ReRAM devices have Ag/Ag-doped CM:κ-car/Pt structure on both oxidized silicon (SiO2/Si) and PET substrates (substrate size of 1.5 cm×1.5 cm). A 10 nm Ti layer as the adhesion layer was deposited using an e-beam evaporator in a vacuum of ~6×10-6 Torr. A 100 nm Pt bottom electrode was deposited by sputtering. CM:κ-car powder was dissolved in 1% acetic acid solution in distilled water with continuous stirring, then filtered through a syringe filter; then 1 wt %. AgNO3 powder (≥99.9999, Sigma-Aldrich, CAS number: 7761-88-8) was added into the CM:κ-car. The CM:κ-car solution was spin-coated on substrates with Pt bottom electrode. The Ag-doped CM:κ-car film was dried at room temperature for 12 h. Finally, Ag top electrodes with diameter of 100 µm and thickness of 100 nm were deposited by thermal evaporation through a shadow mask. κ-car and undoped CM:κ-car devices were fabricated in the same way with κ-car and CM:κ-car powder. κ-car, CM:κ-car, and Ag-doped CM:κ-car on Pt/SiO2/Si substrate showed 10 Environment ACS Paragon Plus

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the similar thickness (~100 nm). These values are similar to previous reported RRAM based on biomaterials. The thickness of the layers was determined by SEM images (Figure S5). 4.2 Characterization. All electrical characteristics were measured at atmospheric pressure and room temperature (RT). The semiconductor parameter analyzer (4200-SCS, KEITHLEY) was used to measure the current-voltage (I-V) curve and data retention. The current response of voltage pulses and AC endurance were measured using a waveform generator (33621A, KEYSIGHT) and oscilloscope (TDS 5054, TEKTRONIX). The response time of devices was tested by applying a single set or reset pulse to the device from a waveform generator. Then an I-V sweep with the semiconductor parameter analyzer was conducted to determine the device states. During electrical measurements, the Pt bottom electrode was electrically grounded, and external bias was applied to the Pt top electrode. An optical microscopy image of memory devices was captured by an optical microscope (LV100ND, Nikon). Cross-sectional SEM images of κ-car, CM:κ-car, and Ag-doped CM:κ-car thin film were captured using high-resolution field-emission scanning electron microscopy (JSM-7401F, JEOL).

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Figures

Figure 1. (a) Schematic diagram of Ag/Ag-doped CM:κ-car/Pt, (b) Typical I-V curve of Ag/Ag-doped CM:κ-car/Pt under low compliance current (10-5 A).

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Figure 2. (a) I-V curves of Ag/Ag-doped CM:κ-car/Pt devices obtained from 20 devices. Inset: an optical microscopy image of memory devices (scale bar: 200 µm). (b) Distributions of current levels of HRS and LRS from 20 devices under 0.02 V read voltage. (c) Data retention characteristic. (d) Set process by voltage pulse with 0.4 V and 50 ns. Inset: the applied pulse.

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Figure 3. (a) Reset current and reset voltages of biomemristors including the κ-car-based devices (this work). (b) Low power consumption of κ-car-based devices.

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Figure 4. Schematic illustrations of suggested switching mechanism. (a-c) mechanism of unidirectional threshold resistive switching, (a) Pristine undoped CM:κ-car device structure without Ag+ ions in biopolymer matrix, (b) weak filament formation by reduction of Ag+ ions generated from Ag top electrode by oxidation, (c) spontaneous filament rupture after applying voltage, (d-f) mechanism of nonvolatile resistive switching, (d) Pristine Ag-doped CM:κ-car device structure with Ag+ ions in biopolymer matrix, (e) thick filament formation by reduction of Ag+ ions generated by oxidation from Ag top electrode and pre-existing Ag+ ions, (f) filament rupture by Joule heating and the presence of the electric field.

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Figure 5. The feasibility of κ-car-based flexible devices. Resistive switching of Ag/Ag-doped CM:κcar/Pt/Ti/PET under (a) tensile and (b) compressive bending; Inset (left) schematic diagram of device during bending, (right): photograph of bent device.

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ASSOCIATED CONTENT Supporting Information. I-V characteristic of κ-car and CM:κ-car device under compliance current of 10-4 A, breakdown failure during unipolar mode, Endurance behavior of Ag/Ag-doped CM:κ-car/Pt with stable switching, Measured and fitted log scale I - V curve of Ag/Ag-doped CM:κ-car/Pt device and Endurance behavior of Ag-doped CM:κ-car device on flexible substrate is included. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] (J.-S.L) Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This

work

was

supported

by

National

Research

Foundation

of

Korea

(NRF-

2016M3D1A1027663). This work was also supported by Future Semiconductor Device Technology Development Program (10045226) funded by the Ministry of Trade, Industry & Energy (MOTIE)/Korea Semiconductor Research Consortium (KSRC). In addition, this work was partially supported by Brain Korea 21 PLUS project (Center for Creative Industrial Materials). ABBREVIATIONS

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κ-car, κ-carrageenan; CM:κ-car, carboxymethyl κ-carrageenan; ReRAM, resistive switching random access memory; CC, compliance current; HRS, high-resistance state; LRS, lowresistance state

REFERENCES 1. Pan, F.; Gao, S.; Chen, C.; Song, C.; Zeng, F. Recent Progress in Resistive Random Access Memories: Materials, Switching Mechanisms, and Performance. Mater. Sci. Eng. R-Rep. 2014, 83, 1-59. 2. Choi, J.; Park, S.; Lee, J.; Hong, K.; Kim, D. H.; Moon, C. W.; Park, G. D.; Suh, J.; Hwang, J.; Kim, S. Y.; Jung, H. S.; Park, N. G.; Han, S.; Nam, K. T.; Jang, H. W. Organolead Halide Perovskites for Low Operating Voltage Multilevel Resistive Switching. Adv. Mater. 2016, 28, 6562-6567. 3. Lee, M. J.; Lee, C. B.; Lee, D.; Lee, S. R.; Chang, M.; Hur, J. H.; Kim, Y. B.; Kim, C. J.; Seo, D. H.; Seo, S.; Chung, U. I.; Yoo, I. K.; Kim, K. A Fast, High-Endurance and Scalable NonVolatile Memory Device Made from Asymmetric Ta2O(5-x)/TaO(2-x) Bilayer Structures. Nat. Mater. 2011, 10, 625-630. 4. Gu, C.; Lee, J. S. Flexible Hybrid Organic-Inorganic Perovskite Memory. ACS Nano 2016, 10, 5413-5418. 5. Kim, M.-K.; Lee, J.-S. Design of Electrodeposited Bilayer Structures for Reliable Resistive Switching with Self-Compliance. ACS Appl. Mater. Interfaces 2016, 8, 32918-32924. 6. Park, Y.; Lee, J.-S. Flexible Multistate Data Storage Devices Fabricated Using Natural Lignin at Room Temperature. ACS Appl. Mater. Interfaces 2017, 9, 6207-6212. 7. Akbari, M.; Kim, M.-K.; Kim, D.; Lee, J.-S. Reproducible and Reliable Resistive Switching Behaviors of AlOx/HfOx Bilayer Structures with Al Electrode by Atomic Layer Deposition. RSC Advances 2017, 7, 16704-16708. 8. Gao, S.; Song, C.; Chen, C.; Zeng, F.; Pan, F. Dynamic Processes of Resistive Switching in Metallic Filament-Based Organic Memory Devices. J. Phys. Chem. C 2012, 116, 1795517959. 9. Hu, B.; Zhu, X.; Chen, X.; Pan, L.; Peng, S.; Wu, Y.; Shang, J.; Liu, G.; Yan, Q.; Li, R. W. A Multilevel Memory Based on Proton-Doped Polyazomethine with an Excellent Uniformity in Resistive Switching. J. Am. Chem. Soc. 2012, 134, 17408-17411. 10. Wu, S. M.; Tsuruoka, T.; Terabe, K.; Hasegawa, T.; Hill, J. P.; Ariga, K.; Aono, M. A Polymer-Electrolyte-Based Atomic Switch. Adv. Funct. Mater. 2011, 21, 93-99. 11. Krishnan, K.; Tsuruoka, T.; Mannequin, C.; Aono, M. Mechanism for Conducting Filament Growth in Self-Assembled Polymer Thin Films for Redox-Based Atomic Switches. Adv. Mater. 2016, 28, 640-648. 12. Meng, F.; Jiang, L.; Zheng, K.; Goh, C. F.; Lim, S.; Hng, H. H.; Ma, J.; Boey, F.; Chen, X. Protein-Based Memristive Nanodevices. Small 2011, 7, 3016-3020. 13. Gogurla, N.; Mondal, S. P.; Sinha, A. K.; Katiyar, A. K.; Banerjee, W.; Kundu, S. C.; Ray, S. K. Transparent and Flexible Resistive Switching Memory Devices with a Very High ON/OFF Ratio Using Gold Nanoparticles Embedded in a Silk Protein Matrix. Nanotechnology 2013, 24, 345202.

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14. Wang, H.; Meng, F.; Cai, Y.; Zheng, L.; Li, Y.; Liu, Y.; Jiang, Y.; Wang, X.; Chen, X. Sericin for Resistance Switching Device with Multilevel Nonvolatile Memory. Adv. Mater. 2013, 25, 5498-5503. 15. Chang, Y. C.; Wang, Y. H. Resistive Switching Behavior in Gelatin Thin Films for Nonvolatile Memory Application. ACS Appl. Mater. Interfaces 2014, 6, 5413-5421. 16. Chen, Y. C.; Yu, H. C.; Huang, C. Y.; Chung, W. L.; Wu, S. L.; Su, Y. K. Nonvolatile Bio-Memristor Fabricated with Egg Albumen Film. Sci. Rep. 2015, 5, 10022. 17. Wang, H.; Du, Y. M.; Li, Y. T.; Zhu, B. W.; Leow, W. R.; Li, Y. G.; Pan, J. S.; Wu, T.; Chen, X. D. Configurable Resistive Switching between Memory and Threshold Characteristics for Protein-Based Devices. Adv. Funct. Mater. 2015, 25, 3825-3831. 18. Wang, H.; Zhu, B.; Wang, H.; Ma, X.; Hao, Y.; Chen, X. Ultra-Lightweight Resistive Switching Memory Devices Based on Silk Fibroin. Small 2016, 12, 3360-3365. 19. Zhang, C.; Shang, J.; Xue, W.; Tan, H.; Pan, L.; Yang, X.; Guo, S.; Hao, J.; Liu, G.; Li, R. W. Convertible Resistive Switching Characteristics between Memory Switching and Threshold Switching in a Single Ferritin-Based Memristor. Chem. Commun. 2016, 52, 48284831. 20. Ko, Y.; Kim, Y.; Baek, H.; Cho, J. Electrically Bistable Properties of Layer-by-Layer Assembled Multilayers Based on Protein Nanoparticles. ACS Nano 2011, 5, 9918-9926. 21. Nagashima, K.; Koga, H.; Celano, U.; Zhuge, F.; Kanai, M.; Rahong, S.; Meng, G.; He, Y.; De Boeck, J.; Jurczak, M.; Vandervorst, W.; Kitaoka, T.; Nogi, M.; Yanagida, T. Cellulose Nanofiber Paper as an Ultra Flexible Nonvolatile Memory. Sci. Rep. 2014, 4, 5532. 22. Raeis, H. N.; Lee, J.-S. Biocompatible and Flexible Chitosan-Based Resistive Switching Memory with Magnesium Electrodes. Adv. Funct. Mater. 2015, 25, 5586-5592. 23. Raeis, H. N.; Lee, J.-S. Controlling the Resistive Switching Behavior in Starch-Based Flexible Biomemristors. ACS Appl. Mater. Interfaces 2016, 8, 7326-7332. 24. Raeis, H. N.; Lee, J.-S. Resistive Switching Memory Based on Bioinspired Natural Solid Polymer Electrolytes. ACS Nano 2015, 9, 419-426. 25. Kim, M.-K.; Lee, J.-S. Short-Term Plasticity and Long-Term Potentiation in Artificial Biosynapses with Diffusive Dynamics. ACS Nano 2018, DOI: 10.1021/acsnano.7b08331. 26. Hierold, C.; Clasbrummel, B.; Behrend, D.; Scheiter, T.; Steger, M.; Oppermann, K.; Kapels, H.; Landgraf, E.; Wenzel, D.; Etzrodt, D. Low Power Integrated Pressure Sensor System for Medical Applications. Sens. Actuators, A 1999, 73, 58-67. 27. Haider, M. R.; Islam, S. K.; Mostafa, S.; Mo, Z.; Taeho, O. Low-Power Low-Voltage Current Readout Circuit for Inductively Powered Implant System. IEEE Trans. Biomed. Circuits Syst. 2010, 4, 205-213. 28. Necas, J.; Bartosikova, L. Carrageenan: A Review. Vet Med 2013, 58, 187-205. 29. Di Palma, T.; Migliardini, F.; Caputo, D.; Corbo, P. Xanthan and Κ-Carrageenan Based Alkaline Hydrogels as Electrolytes for Al/Air Batteries. Carbohydr. Polym. 2017, 157, 122-127. 30. Peng, X. Y.; Chu, J.; Aldalbahi, A.; Rivera, M.; Wang, L. D.; Duan, S. K.; Feng, P. A Flexible Humidity Sensor Based on Kc-Mwcnts Composites. Appl. Surf. Sci. 2016, 387, 149154. 31. Mobarak, N. N.; Jumaah, F. N.; Ghani, M. A.; Abdullah, M. P.; Ahmad, A. Carboxymethyl Carrageenan Based Biopolymer Electrolytes. Electrochim. Acta 2015, 175, 224231.

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32. Bella, F.; Mobarak, N. N.; Jumaah, F. N.; Ahmad, A. From Seaweeds to Biopolymeric Electrolytes for Third Generation Solar Cells: An Intriguing Approach. Electrochim. Acta 2015, 151, 306-311. 33. Mobarak, N. N.; Ramli, N.; Ahmad, A.; Rahman, M. Y. A. Chemical Interaction and Conductivity of Carboxymethyl Kappa-Carrageenan Based Green Polymer Electrolyte. Solid State Ionics 2012, 224, 51-57. 34. Fan, L. H.; Wang, L. B.; Gao, S.; Wu, P. H.; Li, M. J.; Xie, W. G.; Liu, S. H.; Wang, W. P. Synthesis, Characterization and Properties of Carboxymethyl Kappa Carrageenan. Carbohydr. Polym. 2011, 86, 1167-1174. 35. Leong, K. H.; Chung, L. Y.; Noordin, M. I.; Mohamad, K.; Nishikawa, M.; Onuki, Y.; Morishita, M.; Takayama, K. Carboxymethylation of Kappa-Carrageenan for Intestinal-Targeted Delivery of Bioactive Macromolecules. Carbohydr. Polym. 2011, 83, 1507-1515. 36. Balian, S. R. C.; Ahmad, A.; Mohamed, N. S. The Effect of Lithium Iodide to the Properties of Carboxymethyl -Carrageenan/Carboxymethyl Cellulose Polymer Electrolyte and Dye-Sensitized Solar Cell Performance. Polymers 2016, 8, 163. 37. Yang, Y.; Gao, P.; Li, L.; Pan, X.; Tappertzhofen, S.; Choi, S.; Waser, R.; Valov, I.; Lu, W. D. Electrochemical Dynamics of Nanoscale Metallic Inclusions in Dielectrics. Nat. Commun. 2014, 5, 4232. 38. Valov, I.; Lu, W. D. Nanoscale Electrochemistry Using Dielectric Thin Films as Solid Electrolytes. Nanoscale 2016, 8, 13828-13837. 39. La Barbera, S.; Vuillaume, D.; Alibart, F. Filamentary Switching: Synaptic Plasticity through Device Volatility. ACS Nano 2015, 9, 941-949. 40. Hsiung, C. P.; Liao, H. W.; Gan, J. Y.; Wu, T. B.; Hwang, J. C.; Chen, F.; Tsai, M. J. Formation and Instability of Silver Nanofilament in Ag-Based Programmable Metallization Cells. ACS Nano 2010, 4, 5414-5420. 41. Wang, Z.; Joshi, S.; Savel’ev, S. E.; Jiang, H.; Midya, R.; Lin, P.; Hu, M.; Ge, N.; Strachan, J. P.; Li, Z. Memristors with Diffusive Dynamics as Synaptic Emulators for Neuromorphic Computing. Nat. Mater. 2017, 16, 101-108. 42. Song, J.; Prakash, A.; Lee, D.; Woo, J.; Cha, E.; Lee, S.; Hwang, H. Bidirectional Threshold Switching in Engineered Multilayer (Cu2O/Ag:Cu2O/Cu2O) Stack for Cross-Point Selector Application. Appl. Phys. Lett. 2015, 107, 113504. 43. Yang, Y. C.; Pan, F.; Liu, Q.; Liu, M.; Zeng, F. Fully Room-Temperature-Fabricated Nonvolatile Resistive Memory for Ultrafast and High-Density Memory Application. Nano Lett. 2009, 9, 1636-1643. 44. Waser, R.; Dittmann, R.; Staikov, G.; Szot, K. Redox-Based Resistive Switching Memories - Nanoionic Mechanisms, Prospects, and Challenges. Adv. Mater. 2009, 21, 26322663. 45. Gao, S.; Song, C.; Chen, C.; Zeng, F.; Pan, F. Formation Process of Conducting Filament in Planar Organic Resistive Memory. Appl. Phys. Lett. 2013, 102, 141606. 46. Cho, B.; Yun, J. M.; Song, S.; Ji, Y.; Kim, D. Y.; Lee, T. Direct Observation of Ag Filamentary Paths in Organic Resistive Memory Devices. Adv. Funct. Mater. 2011, 21, 39763981. 47. Yoo, J.; Woo, J.; Song, J.; Hwang, H. Threshold Switching Behavior of Ag-Si Based Selector Device and Hydrogen Doping Effect on Its Characteristics. AIP Adv. 2015, 5, 127221. 48. Krishnan, K.; Aono, M.; Tsuruoka, T. Kinetic Factors Determining Conducting Filament Formation in Solid Polymer Electrolyte Based Planar Devices. Nanoscale 2016, 8, 13976-13984.

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49. Park, K.; Lee, J. S. Flexible Resistive Switching Memory with a Ni/Cuo X /Ni Structure Using an Electrochemical Deposition Process. Nanotechnology 2016, 27, 125203. 50. Lai, Y. C.; Wang, Y. X.; Huang, Y. C.; Lin, T. Y.; Hsieh, Y. P.; Yang, Y. J.; Chen, Y. F. Rewritable, Moldable, and Flexible Sticker- Type Organic Memory on Arbitrary Substrates. Adv. Funct. Mater. 2014, 24, 1430-1438.

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