Simplified ZrTiOx-based RRAM cell structure with rectifying characteristics by integrating Ni/n + -Si diode

Abstract

A simplified one-diode one-resistor (1D1R) resistive switching memory cell that uses only four layers of TaN/ZrTiOx/Ni/n+-Si was proposed to suppress sneak current where TaN/ZrTiOx/Ni can be regarded as a resistive-switching random access memory (RRAM) device while Ni/n+-Si acts as an Schottky diode. This is the first RRAM cell structure that employs metal/semiconductor Schottky diode for current rectifying. The 1D1R cell exhibits bipolar switching behavior with SET/RESET voltage close to 1 V without requiring a forming process. More importantly, the cell shows tight resistance distribution for different states, significantly rectifying characteristics with forward/reverse current ratio higher than 103 and a resistance ratio larger than 103 between two states. Furthermore, the cell also displays desirable reliability performance in terms of long data retention time of up to 104 s and robust endurance of 105 cycles. Based on the promising characteristics, the four-layer 1D1R structure holds the great potential for next-generation nonvolatile memory technology. © 2014 Lin et al.; licensee Springer.