Resistive Random Access Memory Enabled by Carbon Nanotube Crossbar Electrodes

We use single-walled carbon nanotube (CNT) crossbar electrodes to probe sub-5 nm memory domains of thin AlO_<i>x</i> films. Both metallic and semiconducting CNTs effectively switch AlO_<i>x</i> bits between memory states with high and low resistance. The low-resistance state scales linearly with CNT series resistance down to ∼10 MΩ, at which point the ON-state resistance of the AlO_<i>x</i> filament becomes the limiting factor. Dependence of switching behavior on the number of cross-points suggests a single channel to dominate the overall characteristics in multi-crossbar devices. We demonstrate ON/OFF ratios up to 5 × 10⁵ and programming currents of 1 to 100 nA with few-volt set/reset voltages. Remarkably low reset currents enable a switching power of 10–100 nW and estimated switching energy as low as 0.1–10 fJ per bit. These results are essential for understanding the ultimate scaling limits of resistive random access memory at single-nanometer bit dimensions