Light‐Assisted Resistive Switching Memory Device with Reduced SET/RESET Voltage Using Sol–Gel TiO2 on Al‐Doped ZnO Electrode

Abstract

Herein, light‐assisted resistive switching (RS) characteristic of low‐cost sol–gel TiO2 film‐based metal–insulator–metal (MIM) configuration using Al‐doped ZnO (AZO) as the bottom electrode is demonstrated. Unprecedentedly, instead of the costly transparent conducting electrode such as tin‐doped indium oxide, AZO electrode is exploited in this study due to its dual role as a transparent and an additional oxygen vacancy (VO)‐rich electrode. The Al/TiO2/AZO device shows electroforming free bipolar RS characteristics, which can be explained by the formation (rupture) of conducting filaments composed of VO. The memory window is increased three times under the blue light illumination compared to dark conditions. Interestingly, the SET and RESET voltages are decreased from 5.2 to 4.5 V and −3.9 to −3.3 V, respectively, under the blue light illumination with respect to the dark condition. The enhancement in the RS effect under the blue light illumination is explained in terms of the photoresponsive properties of TiO2. The MIM device exhibits good switching repeatability with stable retention characteristics, making them attractive for next‐generation nonvolatile resistive random access memory devices.