Oxygen vacancy modulation and enhanced switching behavior in HfOx film induced by Al doping effect

Abstract

The effect of Al doping concentration on resistive switching characteristics of Pt/Al-doped HfOx/Cu structures was investigated. According to the X-ray photoelectron spectroscopy (XPS) analysis and the first-principle calculation, the Al doping introduced more oxygen vacancies in HfOx film and these oxygen vacancies can be easily generated along Al dopants. Significant enhancement in resistive switching behaviors was achieved for 6.8% Al-doped HfOx film in terms of ON/OFF ratio, switching voltages and uniformity, whereas the higher Al doping concentration of 9.4% caused excess oxygen vacancies in the film, resulting in the degeneration of switching performance. A schematic diagram based on the formation and rupture of oxygen vacancy filaments was proposed to illustrate the distinct switching behaviors of HfOx and Al-doped HfOx samples. The results indicated that the concentration and distribution of oxygen vacancies played an important role on resistive switching behavior. The reliability properties for the prepared HfOx samples were also investigated. This work might provide a guidance for the further optimization of HfOx-based memory.