Improved Intrinsic Nonlinear Characteristics of Ta(2)O(5)/Al(2)O(3)-Based Resistive Random-Access Memory for High-Density Memory Applications

The major hindrance for high-density application of two-terminal resistive random-access memory (RRAM) array design is unintentional sneak path leakage through adjacent cells. Herein, we propose a bilayer structure of Ta(2)O(5)/Al(2)O(3)-based bipolar type RRAM by evaluating the intrinsic nonlinear characteristics without integration with an additional transistor and selector device. We conducted X-ray photoelectron spectroscopy (XPS) analysis with different etching times to verify Ta(2)O(5)/Al(2)O(3) layers deposited on the TiN bottom electrode. The optimized nonlinear properties with current suppression are obtained by varying Al(2)O(3) thickness. The maximum nonlinearity (~71) is achieved in a Ta(2)O(5)/Al(2)O(3) (3 nm) sample. Furthermore, we estimated the comparative read margin based on the I-V characteristics with different thicknesses of Al(2)O(3) film for the crossbar array applications. We expect that this study about the effect of the Al(2)O(3) tunnel barrier thickness on Ta(2)O(5)-based memristors could provide a guideline for developing a selector-less RRAM application.