Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan.
ACS Appl Mater Interfaces. 2011 Jul;3(7):2616-21. doi: 10.1021/am200430y. Epub 2011 Jul 7.
In this work, a tungsten oxide (WO(x)) film is prepared using a thiourea-assisted solution process. We demonstrate a device composed of fluorine doped tin oxide (FTO)-glass/WO(x)/electrolyte/indium-tin oxide (ITO)-glass stacking electrochromic (EC) structure and Al electrodes that are locally patterned and interposed between the WO(x) film and electrolyte, which form an Al(top electrode)/WO(x)/FTO(bottom electrode) resistance random access memory (RRAM) unit. According to transmission electron microscopy and X-ray photoelectron spectroscopy analyses, the WO(x) film contains nanosize pores and metallic-tungsten nanoclusters which are scattered within the tungsten oxide layer and concentrated along the interface between the Al electrode and WO(x) film. With application of voltage to the ITO electrode, multiple transmittance states are achieved for the EC unit due to the different quantity of intercalated Li ions in the WO(x) film. As for the Al/WO(x)/FTO RRAM unit, a bipolar nonvolatile resistive switching behavior is attained by applying voltage on the Al top electrode, showing electrical bistability with an ON/OFF current ratio up to 1 × 10(4).
在这项工作中，使用硫脲辅助的溶液法制备了氧化钨 (WO(x)) 薄膜。我们展示了一种由掺氟氧化锡 (FTO)-玻璃/WO(x)/电解质/铟锡氧化物 (ITO)-玻璃堆叠电致变色 (EC) 结构和 Al 电极组成的器件，Al 电极局部图案化并夹在 WO(x) 薄膜和电解质之间，形成 Al(顶电极)/WO(x)/FTO(底电极)阻变随机存取存储器 (RRAM) 单元。根据透射电子显微镜和 X 射线光电子能谱分析，WO(x) 薄膜含有纳米尺寸的孔和金属钨纳米团簇，这些纳米团簇分散在氧化钨层中，并沿 Al 电极和 WO(x) 薄膜之间的界面集中。通过向 ITO 电极施加电压，EC 单元实现了多个透过率状态，这是由于 WO(x) 薄膜中插入的 Li 离子数量不同。对于 Al/WO(x)/FTO RRAM 单元，通过在 Al 顶电极上施加电压，获得了双极性非易失性电阻开关行为，表现出电双稳性，导通/关断电流比高达 1×10(4)。
