Silver/(sub-10 nm)hafnium-oxide-based resistive switching devices on silicon: characteristics and switching mechanism

This study investigates the resistive switching (RS) behavior of Ag/HfO₂(3 nm-thick)/SiO _x (interfacial-layer)/Si devices. The findings are drawn from a systematic electrical and material characterization of the fabricated devices. Based on the current-time (I-t) and current-voltage (I-V) measurements, it is inferred that both metal and oxygen ion migration play a significant role in the switching events, leading to bipolar and unipolar switching modes depending on the biasing scheme. The results demonstrate two competing switching mechanisms taking place when the biasing voltage is increased beyond the RESET voltage in the bipolar mode. The devices are also shown to exhibit self-rectifying characteristics when the bias is applied to the Ag electrode. The proposed method of investigating the total charge passed through the device within the time to SET, during the I-t characterization, is particularly useful for identifying the current transport models governing the high-resistance state. The results reported in this manuscript provide useful insights into the control of RS behavior in this scientifically and technologically important material system. Developing a thorough understanding of the fundamental physics governing the observed RS behavior is a substantial step for the growing progress in the memristor device research, as well as for its potential exploitation in diverse CMOS-compatible applications.