Laser-Assisted Interface Engineering for Functional Interfacial Layer of Al/ZnO/Al Resistive Random Access Memory (RRAM)

In oxide-based RRAMs using reactive electrodes such as Al, the properties of spontaneously formed interfacial layers are critical factors in determining the resistive switching (RS) performance and reliability. This interfacial layer can provide the beneficial function of oxygen reservoir and series resistance, but is very labile and prone to deterioration, causing fatal reliability problems. Moreover, there are technical difficulties in manipulating and improving the functional interfacial layer due to the various interaction dynamics near the interface and the unstable thermodynamic properties of Al. In this work, laser-assisted interface engineering, which allows exquisite manipulation of the labile interfacial layer, is proposed to improve the reliability and performance of Al/ZnO/Al RRAMs. In addition to photothermal and photochemical effects, the proposed laser process enables fine control over out-diffusions of Al atoms in the vicinity of the ZnO/Al interface, forming a robust interfacial layer with a uniform morphology and abundant oxygen Frenkel pairs. This laser-engineered interfacial layer increases the R-HRS/R-LRS ratio by over 100-fold and reduces R-HRs variation with improved oxygen reservoir ability. It also appears to reduce leakage current and power consumption by acting as a stable series resistance. The correlation between structural and stoichiometric properties of the functional interfacial layer and the performance and reliability of the RRAM is explicated. The results suggest that laser-assisted interface engineering can be one of the most promising methods to implement highly reliable, high-performance Al/ZnO/Al RRAMs.