Fig. 3
HRS/LRS vs. current compliance. a Distribution of HRS and LRS with different current compliances ranging from 1 nA to 500 μA is shown. Different shapes of the Cu filaments are identified by observing the current compliance dependent of both LRS and HRS. Evolution of Cu filament formation and dissolution with different CCs is shown schematically in (b–i). At region I, a Cu nano-chain is formed under b SET and c dissolution under RESET. At region II, a cylindrical filament could be d formed and e under SET and RESET, respectively. At region III, a conical filament could be formed in the GeSex film and dissolved at the Cu/GeSex interface under f SET and g RESET conditions. h A stronger conical-shaped filament could be expected at higher CC of 500 μA under SET. i This stronger filament will be dissolved at the Cu/GeSex interface under RESET