The effect of different metal top electrodes on the performance of solution-processed indium oxide-based RRAM devices

Abstract Indium oxide (In2O3), a well-studied n-type metal oxide, is used as semiconducting oxide in 
FETs due to its high electron mobility, solution-processable, low processing temperature, and 
tuneable electrical properties. It is also a suitable candidate for resistive switching layer and 
semiconducting oxide, which can lead to all oxide 1T1R arrays and transparent electronic 
devices with lower fabrication costs and complexity. However, the performance and 
mechanisms can drastically change depending on the top electrode. Therefore, it is essential to 
investigate suitable top electrode material for In2O3-based RRAM depending on the 
application. Herein, we report a solution-processed crystalline In2O3-based RRAM device with 
different top electrodes (TE) such as copper (Cu), platinum (Pt) and tantalum (Ta). 
Interestingly, the devices were forming-free due to intrinsic oxygen vacancy defects in In2O3 
films. All three TEs exhibited endurance of 103 cycles and stable retention of 103 seconds 
except the Pt TE-based devices, which had minor instability in the HRS. However, regarding 
the HRS/LRS ratio, the Ta TE-based devices showed a relatively higher ratio of 37.5 compared 
to the Cu (1.8) and Pt (~1.63)-based devices. Moreover, devices exhibited abrupt and gradual 
switching depending on the TE. Therefore, this study shows that the choice of TEs influences 
the stability and reliability of In2O3-based RRAM devices and the switching behaviours.