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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.


Relationship among switching thickness, barrier height, and device resistance in the reset process[5].
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Fig6: Relationship among switching thickness, barrier height, and device resistance in the reset process[5].

Mentions: To investigate the switching mechanism, the multiple I-V curves in Figure 5 are fitted to analyze the carrier transport of switching layer. Firstly, a good linear relationship with a slope of 1 was found in the curve of ln(I) versus ln(V), indicating that the carrier transport in LRS is dominated by Ohmic conduction. Furthermore, the different states of reset I-V curves which represent the multi-high-resistance state (multi-HRS) from stage 1 to stage 5 in the Figure 5 were fitted to analyze their carrier transport mechanism. We found that the relationship in the curve of ln(I/T2) versus the square root of the applied voltage (V1/2) is linear. This demonstrated that Schottky emission is considered as the main transport mechanism in multi-HRS during the reset procedure. The major leakage current is contributed from the electrons crossing the potential energy barrier between the interface of switching layer and TiN electrode by the thermionic effect. According to the formula of Schottky emission, , where A** is the Richardson constant, the effective switching thickness (dsw) and energy barrier height (φB) can be obtained from the slope and intercept of the plot of , respectively. The εi = kε0, and the k of HfO2 is about 25. Furthermore, the dsw and φB of different multi-HRS in Figure 5 can also be obtained through calculation. Its dsw and φB versus corresponding resistance for different multi-HRS in Figure 5 are shown in Figure 6. The results exhibit that the φB was fixed about 0.7 eV and independent with corresponding resistance in different multi-HRS. This phenomenon implicates that the switching layer in different multi-HRS showed similar material properties. However, the dsw was increased with the increase of resistance value in different multi-HRS during the reset procedure. The results are attributed to the continuous conduction filament that will be ruptured gradually with the increasing of Vstop, as shown in the insets of upper site of Figure 6.Figure 6


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)

Relationship among switching thickness, barrier height, and device resistance in the reset process[5].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig6: Relationship among switching thickness, barrier height, and device resistance in the reset process[5].
Mentions: To investigate the switching mechanism, the multiple I-V curves in Figure 5 are fitted to analyze the carrier transport of switching layer. Firstly, a good linear relationship with a slope of 1 was found in the curve of ln(I) versus ln(V), indicating that the carrier transport in LRS is dominated by Ohmic conduction. Furthermore, the different states of reset I-V curves which represent the multi-high-resistance state (multi-HRS) from stage 1 to stage 5 in the Figure 5 were fitted to analyze their carrier transport mechanism. We found that the relationship in the curve of ln(I/T2) versus the square root of the applied voltage (V1/2) is linear. This demonstrated that Schottky emission is considered as the main transport mechanism in multi-HRS during the reset procedure. The major leakage current is contributed from the electrons crossing the potential energy barrier between the interface of switching layer and TiN electrode by the thermionic effect. According to the formula of Schottky emission, , where A** is the Richardson constant, the effective switching thickness (dsw) and energy barrier height (φB) can be obtained from the slope and intercept of the plot of , respectively. The εi = kε0, and the k of HfO2 is about 25. Furthermore, the dsw and φB of different multi-HRS in Figure 5 can also be obtained through calculation. Its dsw and φB versus corresponding resistance for different multi-HRS in Figure 5 are shown in Figure 6. The results exhibit that the φB was fixed about 0.7 eV and independent with corresponding resistance in different multi-HRS. This phenomenon implicates that the switching layer in different multi-HRS showed similar material properties. However, the dsw was increased with the increase of resistance value in different multi-HRS during the reset procedure. The results are attributed to the continuous conduction filament that will be ruptured gradually with the increasing of Vstop, as shown in the insets of upper site of Figure 6.Figure 6

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.