Control over Memory Performance of Layer-by-Layer Assembled Metal Phthalocyanine Multilayers via Molecular-Level Manipulation
Control over Memory Performance of Layer-by-Layer Assembled Metal Phthalocyanine Multilayers via Molecular-Level Manipulation
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DOI：
10.1021/cm2033959
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发表时间：
2012-03-27
影响因子：
8.6
通讯作者：
Cho, Jinhan
中科院分区：
文献类型：
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作者：
Koo, Bonkee;Baek, Hyunhee;Cho, Jinhan
我们在此报告了使用静电逐层组装方法制备的铁酞菁多层的非易失性存储特性。阳离子聚(烯丙胺盐酸盐) (PAH) 和阴离子铁(III) 酞菁-4,4,' 4 '', 4'''-四磺酸 (Fe-TsPc) 通过静电相互作用交替沉积在石英玻璃、氧化铟锡 (ITO) 或镀铂硅基底上。从溶液中的循环伏安图 (CV) 获得的 PAH/Fe-TsPc 的电化学响应表明氧化还原反应发生在酞菁单元和金属中心。研究发现，PAH/Fe-TsPc 多层薄膜在溶液中的这些氧化还原反应可以扩展到基于空气中电荷捕获/释放机制的阻变非易失性存储器。夹在底部（铂）和顶部（银或钨）电极之间的PAH/Fe-TsPc多层在低于2 V的相对较低的工作电压下表现出阻变存储器的特性，开关速度约为100 ns，开/关电流比类似于10(3)。此外，使用开尔文探针力显微镜（KPFM）证实，PAH/Fe-TsPc多层膜中的可逆电阻变化主要是由外部施加的电压引起的，这是由于Fe-TsPc内氧化还原位点上电荷的捕获和释放造成的。此外，在相邻Fe-TsPc层之间插入厚度约2nm的绝缘层的情况下，与PAH/Fe-TsPc多层相比，这些器件可以表现出存储性能的进一步改进（开/关电流比类似于10（6））和更低的功耗。
We herein report on the nonvolatile memory properties of iron phthalocyanine multilayers prepared using an electrostatic layer-by-layer assembly method. Cationic poly(allylamine hydrochloride) (PAH) and anionic iron(III) phthalocyanine-4,4,' 4 '', 4'''-tetrasulfonic acid (Fe-TsPc) were alternately deposited onto quartz glass, indium tin oxide (ITO), or platinum-coated silicon substrates via electrostatic interactions. The electrochemical response of the PAH/Fe-TsPc, which was obtained from cyclic voltammograms (CV) in solution, indicated that redox reactions occurred at the phthalocyanine unit and at the metallic center. It was found that these redox reactions of the PAH/Fe-TsPc multilayer films in solution could be extended to resistive switching nonvolatile memory based on a charge trap/release mechanism in air. The PAH/Fe-TsPc multilayers sandwiched between the bottom (platinum) and top (Ag or tungsten) electrodes exhibited the characteristics of a resistive switching memory at a relatively low operating voltage of less than 2 V, with a switching speed of about 100 ns and an ON/OFF current ratio of similar to 10(3). Additionally, it is confirmed using kelvin probe force microscopy (KPFM) that the reversible resistance changes in the PAH/Fe-TsPc multilayers are mainly caused by the externally applied voltage as a result of the trapping and release of charges at redox sites within the Fe-TsPc. Furthermore, in the case where insulating layers of about 2 nm in thickness are inserted between adjacent Fe-TsPc layers, it is demonstrated that these devices can exhibit further improvements in memory performance (ON/OFF current ratio of similar to 10(6)) and a lower power consumption in comparison with PAH/Fe-TsPc multilayers.