Nonpolar electrical switching behavior in Cu–Si(Cu)Ox–Pt stacks

• SiOx films are better compatible with complementary metal-oxide-semiconductors.
• The amorphous structure provides uniform defect-distributed structure.
• Forming-free and non-polar resistive switching behaviors are reproducible and robust.
• Lower operation power density (3 × 104 J/m2) and voltage (± 0.75/± 0.45) are achieved.

Electrical switching of resistive memory is highly interface-dependent. We studied such a switching of Cu-doped amorphous SiOx thin-films in a sandwich stack Cu/Si(Cu)Ox/Pt. The stacks were prepared using radio frequency sputtering except Cu co-doping which utilized direct current (DC) power from 2 W to 15 W. We characterized electrical switching behavior by a Keithley 4200 semiconductor analyzer. Cu/Si(Cu)Ox/Pt devices with Cu-doping at DC-sputtering 2 W exhibit the best switching performance showing reproducible forming-free and non-polar switching. The endurance is more than 102 cycles, electrical resistance ratio more than 10, and operating voltages as low as: ± 0.75 V for SET and ± 0.45 V for RESET. The switching mechanism of Cu/Si(Cu)Ox/Pt stacks is explained based on both filamentary conduction and diffusion of Cu ions/atoms in SiOx. Both ‘temperature coefficient of electrical resistance’ and ‘bonding status’ at different depth-profiles as analyzed by using X-ray photoelectron spectroscopy provide robust evidences of the mechanisms. Cu-doped amorphous SiOx thin-films are thus potential for resistive memory.