Tailoring resistive switching in pulsed laser ablated forming-free hafnia thin films based RRAM devices via digital SET and gradual RESET.

In this work, we have investigated the resistive switching (RS) properties of metal-insulator-metal (MIM) RRAM (resistive random-access memory) devices based on Hafnium Oxide (HfO2) films. A systematic study on the effect of substrate temperature on the crystallinity and its correlation with RS behaviour of HfO2 films deposited on platinized silicon using the Pulsed Laser Deposition (PLD) has been performed. Grazing-incidence X-ray diffraction and X-ray reflectivity techniques were employed to analyse the phase formation and the thickness of the films, respectively. The films were deposited at two different substrate temperatures 400 °C and 700 °C. A lower substrate temperature led to an amorphous film while the higher substrate temperature resulted in a polycrystalline film. The effect of change in amorphous to polycrystalline nature of HfO2 films with substrate temperature was studied on RS behaviour of these films. To assess the RS behaviour, DC electrical characterization was conducted on stacked W/HfO2/Pt thin films. The electrical characterization revealed forming-free bipolar RS behavior in both the films along with a digital SET and gradual RESET. The resistance of the films was found to be dependent on phase and microstructure which in turn depends upon substrate temperature. This study would be useful for the optimization of RS behaviour by tuning the crystallinity of the HfO2 films through processing temperature. [ABSTRACT FROM AUTHOR]