Forming mechanism of Te-based conductive-bridge memories

•The resistive switching of Te-based conductive-bridge memories is investigated in a non-destructive way using hard X-ray photoelectron spectroscopy.•Results highlight the reduction of alumina correlated to the oxidation of zirconium at the ZrTe/Al2O3 interface.•Result also show an enrichment of elemental Te near this interface.•XPS depth profiling confirms the oxygen diffusion towards the top electrode.•A four-layer capacitor model is used to confirm the redox process located at the ZrTe/Al2O3 interface. We investigated origins of the resistivity change during the forming of ZrTe/Al2O3 based conductive-bridge resistive random access memories. Non-destructive hard X-ray photoelectron spectroscopy was used to investigate redox processes with sufficient depth sensitivity. Results highlighted the reduction of alumina correlated to the oxidation of zirconium at the interface between the solid electrolyte and the active electrode. In addition the resistance switching caused a decrease of Zr-Te bonds and an increase of elemental Te showing an enrichment of tellurium at the ZrTe/Al2O3 interface. XPS depth profiling using argon clusters ion beam confirmed the oxygen diffusion towards the top electrode. A four-layer capacitor model showed an increase of both the ZrO2 and AlOx interfacial layers, confirming the redox process located at the ZrTe/Al2O3 interface. Oxygen vacancies created in the alumina help the filament formation by acting as preferential conductive paths. This study provides a first direct evidence of the physico-chemical phenomena involved in resistive switching of such devices.