Interfacial reaction induced digital-to-analog resistive switching in TiO2-based memory devices

Abstract

In the study, TiO2 based resistive random access memory (RRAM) was fabricated by sol-gel technique. By changing the thickness of the TiO2 layer, the devices showed a transition of bipolar digital-type to analog-type memristive behavior under cyclic voltage sweeping process, along with well-defined high and low resistance states. The creation and rupture of nanoscale conductive filaments by drift of the oxygen vacancies was responsible for the digital behavior. The digital-type conduction mechanisms were explained as trap-controlled space charge-limited current conduction mechanism at high resistance state and Ohmic conduction mechanism at low resistance state, respectively. Schottky barrier change induced by the formation of the interfacial layer between Al and TiO2 was responsible for the analog behavior. The analog-type switching mechanisms were explained as trapping and de-trapping of carriers. The interfacial microstructure between TiO2 and electrode would affect the resistive switching behavior of the devices remarkably.