Impact of Stopping Voltage and Hopping Conduction on the Oxygen Vacancy Concentration of Multi-Level HfO2-Based Resistive Switching Devices

A multi-level state HfO
2
-based resistive switching model is reported, where the increase in stopping voltage (V
stop
) and thus activation energy (E
AC
) is attributed to the depletion of oxygen vacancy (V
o
) concentration (n
c
) during reset. Hopping conduction fittings also indicated a depletion of n
c
due to an increase of V
stop
as shown by an increase of trap-to-trap distance (a) and trap energy (ϕ
T
).