Characteristics of gadolinium oxide resistive switching memory with Pt-Al alloy top electrode and post-metallization annealing

The characteristics of gadolinium oxide (Gd_xO_y) resistive switching memories (RRAMs) with a Pt-Al alloy (5.88 at% Al) top electrode (TE) and the effect of post-metallization annealing (PMA) were investigated. Resistance of high resistance state increased with increasing PMA temperature, achieving a resistance ratio of more than 10⁴ owing to the increased Schottky barrier height between the TE and Gd_xO _y film. The change in set and reset voltages corresponded to the concentration of oxygen vacancies at the TE/Gd_xO_y interface, which was examined by x-ray photoelectron spectroscopy. At the PMA temperatures for higher than 350 °C, the Gd_xO_y RRAMs with Pt-Al alloy TEs presented superior retention behaviour for more than 10⁴ s at a testing temperature of 130 °C. Al diffusion into the Gd_xO_y film to form Al_xO_y at the TE/Gd_xO_y interface is responsible for the retention enhancement because it prevented the oxygen ions from out-diffusion through the Pt grain boundaries.