Full factorial analysis of gradual switching in thermally oxidized memristive devices

Abstract

Memristive devices are promising candidates for synaptic memories in neuromorphic computing systems, but the insufficient reliability of the analog behavior has been a challenge. Lateral oxide scaling with bottom-up technologies such as thermal oxidation, coupled with new device architectures, can improve the reliability. However, the effect of thermal oxide growth on analog device behavior remains unclear. In this study, we fabricate a variety of resistive switching thermal oxides on tantalum electrode surfaces and develop a method for rapid full factorial electrical analysis. The analysis uses 2500 unique control parameter combinations of current limits and RESET-stop-voltages to compare device behavior across millions of modulated current–voltage sweeps. We clarify the mechanisms that shift the device behavior from abrupt towards gradual SET transitions, a desirable characteristic for emulating analog plasticity. We found that a mildly negative differential resistance and an increased internal series resistance at the metal–oxide interface contribute to the stabilization of the gradual SET transitions. These findings highlight the importance of fine-tuning the bottom-up oxide growth for improving switching performance.