M.V. Diamanti, R. Pisoni, A. Cologni, F. Corinto, M.P. Pedeferri
Politecnico di Milano, Italy
pp. 196 - 199
Keywords: memristor, titanium dioxide, anodic oxidation
Today, Si-based flash memory devices represent the most prominent nonvolatile data memory (NVM) because of high density and low fabrication costs. However, they suffer from low endurance, low write speed, and high voltages required for the write operations. To overcome such problems, alternative memory concepts are explored. The research here presented deals with resistance switching random access memories in which redox reactions and nano-ionic transport processes play the key role, i.e., memristive devices based on metal oxides, fabricated by electrochemical anodization of titanium or niobium as inexpensive, room temperature alternative to current fabrication methods. Oxide thickness ranged from few nanometers to hundreds of nanometers. Cyclic voltammetry was employed to record the current-voltage response of the material. A hysteretic behavior was found, with open loops both in the positive and negative quadrants of the I-V diagram. The ratio between high and low resistance states was calculated on the basis of the low and high I-V loop slopes. Several anodizing parameters were varied to test oxides with different thickness, composition and structure, on titanium and in a second phase on niobium. Optimal anodizing conditions were identified and the resulting oxide further analyzed, demonstrating high Roff/Ron ratio.