Sp2 clustering-induced improvement of resistive switching uniformity in Cu/amorphous carbon/Pt electrochemical metallization memory

We studied the influence of sp(2) clustering on resistive switching uniformity in Cu/amorphous carbon/Pt electrochemical metallization memory. Herein, a simple method was utilized to adjust the degree of sp(2) clustering by changing compliance currents (CCs). The small sp(2) clusters within the a-C layer were found to condense into larger clusters with increasing CCs because of the CC-dependent Joule heating effect. Raman spectra experimentally verified the increase of sp(2) cluster diameter with increasing CCs. Importantly, a switching uniformity improvement can be obtained by increasing the degree of sp(2) clustering. The enhanced local electric field around sp(2) clusters can account for the reduction of the Cu conductive filament randomness and corresponding improvement of memory performance.