Bipolar resistive switching memory using bilayer TaO x /WO x 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 >10(5) times and data retention of >10(4) s with a resistance ratio of >10(2) at 85 degrees C. (c) 2012 Elsevier Ltd. All rights reserved.