An attempt to reduce the SET voltage and RESET current of resistive switching (RS) memory was made using a geometric array of nanopeak (NP) structures. Bottoms of anodic porous alumina were used to form the NP structures that act as guides for the formation of conductive filaments that effectively concentrate the electric field. Samples were fabricated with flat surfaces (FS) and with two types of NP structure with different NP pitch. The NP samples provided SET voltages less than 2 V with narrow distributions and the RESET current was lower than that with the FS sample.

We have tried suppressing variation of switching voltages which hinder the practical application of resistive switching random access memory. On the basis of a filament model, fabrication of the top electrode with small enough size against the filament size and confining the filament are thought to be the solutions. In this study, we have investigated the confinement effects on the switching voltage variations using anodic porous alumina with ordered nano holes. Variation of the voltage has a trend to reduce with enlarging the diameters of nano holes by chemical etching. The confinement is very effective to improve the reproducibility of the switching voltages.

Resistive change memory has been expected to be a next generation memory due to high-speed response. However, wide variations of switching voltages are often found in the current–voltage (I–V) characteristics and hinder the practical applications. We have tried suppressing the variation by three tactics based on the filament model; confinement of conductive filaments, concentration of electric field, and preparation of many routes for conductive filaments with the same electrical properties. In this study, we have investigated the combination of concentration of electric field method and preparation of many routes for conductive filaments in the insulator by electrochemical treatment (ET) using sulfuric acid. The I–V curves depend on the ET time. The best result is obtained in the long ET time. With regards to switching voltage distribution, the combination of two methods provide better switching characters than those of single method.