Effects of Al dopants and interfacial layer on resistive switching behaviors of HfO_x film

In this work, Al dopants were introduced into HfO_x film by different methods to modulate the oxygen vacancies in the film or near the interface, and the resistive switching characteristics were investigated. By transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis, an interfacial layer was formed at HfO_x/Al interface. The occurrence of interfacial layer resulted in the larger switching voltages and resistances in LRS for HfO_x/Al/HfO_x and HfO_x/Al samples compared with HfO_x:Al sample with uniform Al dopants and no interface. Besides, the different reset processes for Al-doped HfO_x samples were demonstrated. Much uniform distribution of resistances can be observed for all Al-doped HfO_x samples due to the control of oxygen vacancies by Al doping and the good retention properties were achieved for all samples. The models for underlying physical mechanisms were also proposed to illustrate the switching behaviors of the prepared samples.