Improvement of Resistive Switching Uniformity for Al–Zn–Sn–O-Based Memory Device With Inserting HfO2 Layer

This letter demonstrates the characteristics of a resistive switching memory [resistive random access memory (RRAM)] device with a bilayer structure of aluminum-zinc-tin-oxide (AZTO) and HfO₂-film layers. As for the RRAM operation, the formation and rupture processes of the conductive filaments can be confined in the HfO₂ layer with low-concentration oxygen vacancy. The resistive switching stability and electrical uniformity of bilayer AZTO/HfO₂ RRAM device are obviously enhanced as compared with the one only with a single layer of AZTO film. In addition, a physical mechanism for uniformity improvement is proposed by the localized conduction of conducting filaments.