Bipolar resistive switching memory using bilayer TaOx/WOx films

Resistive switching properties of a memory device in an IrOx/TaOx/WOx/W structure have been investigated. High-resolution transmission electron microscopy image has shown the formation of a bilayer structure of TaOx/WOx which is further confirmed by energy dispersive X-ray spectroscopy and X-ray photo-electron spectroscopy analyses. The underlying switching mechanism is successfully explained by providing various electrical measurements such as device area dependency on set/reset voltage and low resistance state. A model based on oxygen ions migration is then proposed. Cumulative probability plots of essential memory parameters such as set/reset voltage and LRS/HRS show good distribution. The device has shown excellent read endurance of >105 times and data retention of >104 s with a resistance ratio of >102 at 85 °C.

► Resistive switching properties and mechanism of IrOx/TaOx/WOx/W stack are studied.
► HRTEM, EDX and XPS analyses revealed TaOx/WOx bilayer formation.
► Oxygen ions/vacancy migration under the electric field result resistance switching.
► Set/reset voltage and LRS independency on device area prove filamentary conduction.
► Good endurance and data retention are achieved.