Ta2O5 doping effects on the property improvement of HfOx-based RRAMs using co-sputtering deposition method

In this study, Ta2O5-doped HfOx thin films with different concentrations were deposited by cosputtering method and resistive random-access memories (RRAMs) were fabricated with the structure as Pt/HfTaOx/TiN/SiO2/Si. Doping Ta2O5 inhibits film crystallization and generates amorphous thin film with insufficient grain boundaries. Due to the high activation energy of Ta2O5 and the feature of atomic rearrangement, the system always attains a stable configuration. Also, in Ta2O5-doped HfOx-based RRAM, metallic Ta cations not only exhibit a diffusion phenomenon comparable to that of metallic Hf cations, but they also moderately increase the oxygen vacancies required for switching operation, hence preventing low resistance state failure. The proposed devices using 12.55% Ta2O5-doped thin film has the smallest leakage current and widest memory window (> 10⊥2) which is better than the reported data. Besides, the device endurance performances operated under high temperature are also discussed. Preferable Ta2O5 doping concentration is helpful to enhance the memory window of RRAM and its endurance performance as operated under high temperature which is very important for practical applications.