Amorphous Metal Oxide Bilayers to Avoid Sneak‐Path Currents for High‐Density Resistive Memory Arrays

Abstract

Resistance switching devices are potential candidates for future memory applications. However, sneak‐path current issues in crossbar array cause energy and heat dissipation, and it requires additional circuitry for mitigation. To address this, we introduce a hybrid device with functional oxide as bilayer of amorphous strontium titanium oxide (a‐STO) and vanadium oxide (a‐VOx). High‐performance resistive switching material a‐STO is coupled with a‐VOx having fast apolar threshold switching. The hybrid device gives performance equivalent to conventional one resistance switch and one selector architecture with stability of 6000 endurance cycles. Non‐linearity factor of the hybrid device is 4.8, which is slightly higher than only a‐STO device of 4.7. Using I–V measurements, readout margin is calculated, which suggests integration into 104\u2009×\u2009104 array when 10% readout margin is considered at switching ratio of 8. Further, the selector effect using non‐zero‐crossing property of memristors, which reveals six times reduction in OFF current in the hybrid device, is quantified. Compositional analysis along the device cross‐section to understand elemental distribution and interface effects of two unique, multifaceted oxides is presented. As such, in the hybrid structure non‐linearity factor remains nearly constant, while the absolute value of non‐zero‐crossing current is reduced six times, which can reduce the overall sneak current in crossbars.