The bipolar resistive switching and negative differential resistance of NiO films induced by the interface states

The Au/NiO/Pt structure was fabricated by magnetron sputtering on the TiOx/SiO2/Si substrates to investigate the bipolar resistive switching and negative differential resistance in details. The XRD results shows the NiO films have the (111) preferential orientation. XPS measurements shows the Ni3+ exists in NiO films, indicating that the p-type nonstoichiometric nickel oxide films forms. The I-V characteristic curves show that the bipolar resistive switching and negative differential resistance seriously depend on the scan mode of applied voltage. When the applied voltage scans from negative voltage to positive voltage and return to negative voltage, the negative differential resistance is obtained accompanied with the distinct resistive switching characteristic. However, the negative differential resistance characteristic disappears when the applied voltage swept from 0 V to positive voltage and returned to 0 V from negative voltage. This behavior is highly affected by the interface states, located at the interface of Au and p-NiO films, trap and release the holes. The schematic diagram of energy band structure and interface state can clearly depict the trap-and-release process, resulting the bipolar resistive switching accompanied with the negative differential resistance.