AC conductance measurement and analysis of the conduction processes in HfO _x based resistive switching memory

Impedance spectroscopy and AC conductance measurement were performed on HfO _x based resistive switching memory. The f ^β-like AC conductance is observable above a corner frequency for high resistance state (HRS). The index β is about 2 and is independent of DC bias or resistance value of different HRSs, suggesting that electron hopping between the nearest neighbor traps within the conductive filaments (CFs) is responsible for the measured AC conductance. The corner frequency shows up in a lower frequency regime for a higher HRS, indicating that a larger tunneling gap is formed between the electrode and the residual CFs.