Characteristics of low frequency noise in n+Si-HfO2-Ni resistive random access memory

The low frequency noises from n⁺Si-HfO₂-Ni resistive random access memory (RRAM) are measured. The normalized power spectra (S_I/I²) in initial state (IS), in high resistance state (HRS), and in low resistance state (LRS) with bias V below a threshold voltage V_th all show 1/f characteristics, have similar magnitudes, and are nearly bias independent. In contrast, in LRS with bias beyond the threshold voltage, the magnitude of the spectra reduces dramatically with bias especially at very low frequency, while the lineshape changes from 1/f to nearly f independent. A simple model which contains trap-assisted (TA) and filament (CF) conductions is proposed to interpret the noise spectra. In IS, HRS, and LRS with V <; V_th, the noise is mainly induced in the TA area with a wide distribution of trap/detrap time. While in LRS with V > V_th, the noise is mainly induced in the CF with the domination of a smaller trap/detrap time.