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Physical and chemical mechanisms in oxide-based resistance random access memory.

Chang KC, Chang TC, Tsai TM, Zhang R, Hung YC, Syu YE, Chang YF, Chen MC, Chu TJ, Chen HL, Pan CH, Shih CC, Zheng JC, Sze SM - Nanoscale Res Lett (2015)

Bottom Line: Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device.The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process.Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan.

ABSTRACT
In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

No MeSH data available.


Related in: MedlinePlus

Bipolar switching behavior, current-time sampling, and Ln(Q)-time fitting curves for −0.9 and −1.2 V. (a) The typical bipolar switching behavior and the metal-insulator-metal (MIM) device structure and (b) the current-time sampling points of the Ni:SiO2 thin film RRAM device. (c) The Ln(Q)-time fitting curve for −0.9 V constant sampling voltage condition. (d) The Ln(Q)-time fitting curve for −1.2 V constant sampling voltage condition.
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Fig11: Bipolar switching behavior, current-time sampling, and Ln(Q)-time fitting curves for −0.9 and −1.2 V. (a) The typical bipolar switching behavior and the metal-insulator-metal (MIM) device structure and (b) the current-time sampling points of the Ni:SiO2 thin film RRAM device. (c) The Ln(Q)-time fitting curve for −0.9 V constant sampling voltage condition. (d) The Ln(Q)-time fitting curve for −1.2 V constant sampling voltage condition.

Mentions: In this research, the reset voltage is defined as the point when obvious current drop exhibits and sometimes even accompanied with unstable I-V properties. Constant voltage sampling is an electrical measurement method, in which voltage bias sweeps from 0 V to the reset point and then remains unchanged. By keeping the voltage at the reset voltage, we sample the current for a period to obtain the continuing resistance change. The sampling voltage here works much more like a reading voltage, from which we can track the spontaneous chemical reaction triggered by the critical voltage point. And one constant voltage sampling result in the Ni:SiO2 RRAM is shown in Figure 11b. In this figure, the y and x axis represent current and time, respectively. From Figure 11b, we can see that the current still keeps decreasing even if the voltage remains at the reset point. Without increasing the operation voltage, continuous current drop manifests the lasting chemical reaction and this process sustains for more than 20 s. Figure 11c shows the first CVS results, and the sampling voltage is −0.9 V. By calculating Q from measurement results, we draw out the Ln(Q)-time curve, which can be seen in Figure 11c. With the increase of sampling time, Ln(Q) drops linearly within the first 10 s. From the red fitting curve, we find the slope of the Ln(Q)-time curve is −0.14. After the first CVS, another CVS measurement was conducted and the results are shown in Figure 11d. The reset voltage at this time is −1.2 V, but interestingly we get the same slope, which is −0.14. The second CVS lasts for 15 s. The same slope Ln(Q)-time curves implies the same reaction rate constant. It is quite common for RRAM to undergo slight current variation in the reset process owing to the stochastic oxidation reaction, but the same reaction rate constant involved in this random process unveils the similarities between relatively different reset situations. At the beginning of different reset processes, there will be a similar chemical reaction procedure in accordance with the first-order rate law and the reaction rate constant remains the same. Besides, even though the sampling voltages vary each other, the same k confirms the same reaction mechanism. This is quite different from our common view that higher voltage will lead to faster chemical reaction.Figure 11


Physical and chemical mechanisms in oxide-based resistance random access memory.

Chang KC, Chang TC, Tsai TM, Zhang R, Hung YC, Syu YE, Chang YF, Chen MC, Chu TJ, Chen HL, Pan CH, Shih CC, Zheng JC, Sze SM - Nanoscale Res Lett (2015)

Bipolar switching behavior, current-time sampling, and Ln(Q)-time fitting curves for −0.9 and −1.2 V. (a) The typical bipolar switching behavior and the metal-insulator-metal (MIM) device structure and (b) the current-time sampling points of the Ni:SiO2 thin film RRAM device. (c) The Ln(Q)-time fitting curve for −0.9 V constant sampling voltage condition. (d) The Ln(Q)-time fitting curve for −1.2 V constant sampling voltage condition.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388104&req=5

Fig11: Bipolar switching behavior, current-time sampling, and Ln(Q)-time fitting curves for −0.9 and −1.2 V. (a) The typical bipolar switching behavior and the metal-insulator-metal (MIM) device structure and (b) the current-time sampling points of the Ni:SiO2 thin film RRAM device. (c) The Ln(Q)-time fitting curve for −0.9 V constant sampling voltage condition. (d) The Ln(Q)-time fitting curve for −1.2 V constant sampling voltage condition.
Mentions: In this research, the reset voltage is defined as the point when obvious current drop exhibits and sometimes even accompanied with unstable I-V properties. Constant voltage sampling is an electrical measurement method, in which voltage bias sweeps from 0 V to the reset point and then remains unchanged. By keeping the voltage at the reset voltage, we sample the current for a period to obtain the continuing resistance change. The sampling voltage here works much more like a reading voltage, from which we can track the spontaneous chemical reaction triggered by the critical voltage point. And one constant voltage sampling result in the Ni:SiO2 RRAM is shown in Figure 11b. In this figure, the y and x axis represent current and time, respectively. From Figure 11b, we can see that the current still keeps decreasing even if the voltage remains at the reset point. Without increasing the operation voltage, continuous current drop manifests the lasting chemical reaction and this process sustains for more than 20 s. Figure 11c shows the first CVS results, and the sampling voltage is −0.9 V. By calculating Q from measurement results, we draw out the Ln(Q)-time curve, which can be seen in Figure 11c. With the increase of sampling time, Ln(Q) drops linearly within the first 10 s. From the red fitting curve, we find the slope of the Ln(Q)-time curve is −0.14. After the first CVS, another CVS measurement was conducted and the results are shown in Figure 11d. The reset voltage at this time is −1.2 V, but interestingly we get the same slope, which is −0.14. The second CVS lasts for 15 s. The same slope Ln(Q)-time curves implies the same reaction rate constant. It is quite common for RRAM to undergo slight current variation in the reset process owing to the stochastic oxidation reaction, but the same reaction rate constant involved in this random process unveils the similarities between relatively different reset situations. At the beginning of different reset processes, there will be a similar chemical reaction procedure in accordance with the first-order rate law and the reaction rate constant remains the same. Besides, even though the sampling voltages vary each other, the same k confirms the same reaction mechanism. This is quite different from our common view that higher voltage will lead to faster chemical reaction.Figure 11

Bottom Line: Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device.The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process.Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan.

ABSTRACT
In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

No MeSH data available.


Related in: MedlinePlus