Analysis of Memory Effect Induced by Hydrogen Annealing
Analysis of Memory Effect Induced by Hydrogen Annealing
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DOI：
10.7566/jpscp.1.012089
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发表时间：
2014-03
期刊：
影响因子：
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通讯作者：
A. Hanada;H. Miura;T. Notsu;S. Kishida;K. Kinoshita
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文献类型：
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作者：
A. Hanada;H. Miura;T. Notsu;S. Kishida;K. Kinoshita
在用作记忆层的金属氧化物层中引入氧空位对于开发电阻式随机存取存储器（ReRAM）[1]的电阻开关效应至关重要。最近，研究人员报道了由H2退火产生的阻性开关效应。从开关机理的角度出发，阐明氧空缺和氢引入引起的电阻开关的区别是有效的。本研究利用x射线吸收精细结构（XAFS）研究了Pt/Bi2Sr2CaCu2O8+δ (Bi2212)块体单晶/Pt结构中H2退火电阻开关的发展与Cu电子态的关系。采用溅射法在Bi2212表面沉积两个电极，制备了Ptbefore/Bi2212/Ptafter结构。在这里，在沉积一个Pt电极（Ptbefore）后，样品在Ar+H2气氛中退火，然后沉积另一个Pt电极（Ptafter）。通过H2退火[2]，证实了Ptbefore/Bi2212结构中产生了电阻开关效应。图1显示了样品在(i)、（ii）、（iii）和（iv）处的Cu K-edge XAFS光谱[插图左图]，其中每个光谱都通过8.9982 keV的强度进行归一化。在(i)和（iii）中观测到的光谱分别与（ii）和（iv）一致。图1的右图显示了Cu k边XAFS光谱在8.985 keV处的强度映射。较高的强度使得Ptbefore可以从其他区域清晰地识别出来。这些结果表明在Ptbefore有选择性地还原了Bi2212。在Pt的催化作用下，H2退火对Bi2212的强还原是实现电阻开关的关键。[10]年彦斌等，物理学报。Rev. Lett. 98,(2007) 146403。[10] A. Hanada et al.，苹果。理论物理。科学通报，（2012）043507。图1 Cu k边XAFS能谱。8.97 8.98 8.99 9.00 9.01 9.02 9.03 0.0 0.2 0.4 0.6 0.8 1.0 i_Pt之前
The introduction of oxygen vacancies into a metal oxide layer, which is used as a memory layer, is crucial to develop the resistive switching effect of resistive random access memory (ReRAM) [1]. Recently, resistive switching effect that is developed by H2 annealing was reported [2]. It is effective to clarify a difference between resistive switching induced by oxygen vacanciesand hydrogen-introduction, in terms of a switching mechanism elucidation. In this study, we investigated a relation between the development of the resistive switching by H2 annealing and the electronic state of Cu in a Pt/Bi2Sr2CaCu2O8+δ (Bi2212) bulk single crystal/Pt structure using X-ray absorption fine structure (XAFS). Two electrodes were deposited on the surface of Bi2212 by sputtering to produce Ptbefore/Bi2212/Ptafter structure. Here, the sample was annealed in Ar+H2 atmosphere after one Pt electrode (Ptbefore) was deposited, followed by deposition of another Pt electrode (Ptafter). The resistive switching effect was confirmed to be induced in the Ptbefore/Bi2212 structure by H2 annealing [2]. Figure 1 shows Cu K-edge XAFS spectra of the sample at (i), (ii), (iii), and (iv) [left figure of the inset], where each spectrum is normalized by the intensity at 8.9982 keV. The spectra observed at (i) and (iii) agreed respectively with those of (ii) and (iv). The inset (right) of Fig. 1 shows the mapping of the intensity of Cu K-edge XAFS spectrum at 8.985 keV. The higher intensity makes the Ptbefore clearly identifiable from the other area. These results suggest the selective reduction of the Bi2212 at Ptbefore. The strong reduction of Bi2212 by H2 annealing that is assisted by the catalytic effect of Pt is crucial for developing the resistive switching. [1] Y. B. Nian et al., Phys. Rev. Lett. 98, (2007) 146403. [2] A. Hanada et al., Appl. Phys. Lett. 101, (2012) 043507. Fig. 1 Energy spectra of Cu K-edge XAFS. 8.97 8.98 8.99 9.00 9.01 9.02 9.03 0.0 0.2 0.4 0.6 0.8 1.0 i_Pt before