High-Performance InGaZnO-Based ReRAMs

Amorphous indium-gallium-zinc oxide (IGZO) is one of the most promising oxide semiconductors for thin-film transistors and it has started to replace amorphous silicon in display drivers. However, attempts to use IGZO in resistive random access memories (ReRAMs) are still scarce. This work investigates the bipolar resistive switching properties of crossbar-ReRAM devices based on IGZO thin film. Aluminum bottom electrode and two different top electrodes (i.e., Al and Ag) were tested in the devices. It was discovered that an oxygen plasma treatment (OPT) on the bottom electrode could significantly improve the surface roughness of the bottom electrode, the ON/OFF ratio, and the switching uniformity. After the OPT, the endurance of ReRAMs was enhanced. The ON/OFF current ratios reached ~10
⁴
and 10
⁵
within 100 endurance cycles for Al and Ag top electrode devices, respectively. Furthermore, the ReRAMs memory window remained nearly constant during a retention test of 10
⁵
s. The conduction mechanisms of the two device structures were examined using Schottky emission and space-charge-limited-current pictures, and the memory effect was explained by the formation and the interruption of filaments.