Yoo E J, Kang S Y, Shim E L, Yoon T S, Kang C J, Choi Y J
J Nanosci Nanotechnol. 2015 Nov;15(11):8622-6. doi: 10.1166/jnn.2015.11487.
The resistance-switching characteristics of metal oxides have attracted great interest for the non-volatile memory applications such as resistive random access memory. A basic resistive random access memory device has a metal/insulator/metal structure, and its memory effect is achieved by applying voltage to change the resistance of the insulating layer. One of the promising candidates for explaining the resistance-switching mechanism is the formation and rupture of nanoscale conductive filaments. However, this model has an issue that needs to be addressed: the wide distribution of switching voltage due to randomly formed filaments. Therefore, some researchers have reported a decrease in switching voltage distribution and an increase in switching stability by incorporating nanoparticles into the insulating layer. In this study, we investigated influence of incorporated Pt-Fe2O3 core-shell nanoparticles on the resistive switching characteristics of ZnO thin films. Devices were fabricated on SiO2 wafers. A 100-nm-thick Cr layer was used as the bottom electrode. A 50-nm-thick ZnO layer was deposited using the sputtering method, and Pt-Fe2O3 nanoparticles were deposited on it by the dip coating method. A 50-nm-thick ZnO layer was then deposited again. A top Cr electrode (size: 100 μm x 100 μm) was deposited using a shadow mask and sputtering system. All the devices showed bipolar resistance-switching behavior that is observed in Cr/ZnO/Cr structures. However, the on/off voltage was dramatically lowered by incorporating nanoparticles into the insulating layer when compared with that of the devices without nanoparticles. In addition, the switching stability of the devices was improved upon the incorporation of nanoparticles. On the basis of these results, we can conclude that Pt-Fe2O3 nanoparticles may be used to enhance the resistance switching properties of ZnO thin films by incorporating them into the films.
金属氧化物的电阻切换特性在诸如电阻式随机存取存储器等非易失性存储器应用中引起了极大的兴趣。基本的电阻式随机存取存储器器件具有金属/绝缘体/金属结构，其存储效应是通过施加电压来改变绝缘层的电阻实现的。用于解释电阻切换机制的一个有前景的候选者是纳米级导电细丝的形成和断裂。然而，该模型有一个需要解决的问题：由于细丝随机形成导致开关电压分布较宽。因此，一些研究人员报告称，通过将纳米颗粒掺入绝缘层中，开关电压分布会降低，开关稳定性会提高。在本研究中，我们研究了掺入的Pt-Fe2O3核壳纳米颗粒对ZnO薄膜电阻切换特性的影响。器件在SiO2晶圆上制造。使用100nm厚的Cr层作为底部电极。通过溅射法沉积50nm厚的ZnO层，并通过浸涂法在其上沉积Pt-Fe2O3纳米颗粒。然后再次沉积50nm厚的ZnO层。使用荫罩和溅射系统沉积顶部Cr电极（尺寸：100μm×100μm）。所有器件都表现出在Cr/ZnO/Cr结构中观察到的双极电阻切换行为。然而，与没有纳米颗粒的器件相比，当在绝缘层中掺入纳米颗粒时，开/关电压显著降低。此外，掺入纳米颗粒后器件的开关稳定性得到改善。基于这些结果，我们可以得出结论，通过将Pt-Fe2O3纳米颗粒掺入ZnO薄膜中，可以用于增强其电阻切换性能。
