Capacitive and RRAM Forming-Free Memory Behavior of Electron-Beam Deposited Ta2O5 Thin Film for Nonvolatile Memory Application

The present study reports the presence of capacitive memory and forming-free resistive random access memory (RRAM) in a tantalum pentoxide (Ta2O5) thin film (TF) device. The capacitance and voltage analysis of the electron-beam evaporated Ta2O5 TF device exhibits three distinct regimes: inversion, depletion, and accumulation, which decrease as the frequency of operation increases. This behavior is attributed to the interface state density (Dit) and series resistance (Rs). Moreover, the memory window of the Ta2O5 device was found to increase from 1.2 (± 1 V) to 7.9 (± 10 V). Furthermore, the resistive switching mechanism was investigated through the current (I) vs voltage (V) measurement for 1000 cycles. The device exhibits abnormal forming-free bipolar resistive switching. In addition, a desirable and stable switching behavior with resistance ratio of 102 and a retention up to 103 s at +2.5 V was observed. The overall findings of the Au/Ta2O5 TF/Si device could provide a pave way for nonvolatile memory (NVM) application.