Mechanisms of conductive filament formation in hafnium oxide multilayer structures

The paper describes an investigation of resistive switching in the Pt/HfO2/HfOxNy/TiN, Pt/HfO2/TaOxNy/TiN, and Pt/Al2O3/HfO2/TaOxNy/TiN structures with oxide layers deposited by atomic layer deposition. Using conductive atomic force microscopy, we demonstrate the formation of conductive filaments in every structure. We also perform a complete resistive switching cycle. We define the properties of the filaments formed at different voltages and present the size and conductivity distributions of the filaments. Our research confirms that filaments in amorphous hafnium oxide initiate on the film defects, however, defects at different materials interfaces can enhance filament density in structures with different oxide layers. It appears that among the presented structures, the Pt/Al2O3/HfO2/TaOxNy/TiN structure has the greatest potential for use in resistive random-access memory.