Low-Frequency Noise-Based Mechanism Analysis of Endurance Degradation in Al/αTiO_x/Al Resistive Random Access Memory Devices

In this work, we analyze a resistive switching random access memory (RRAM) device with the metal–insulator–metal structure of Al/αTiO_x/Al. The transport mechanism of our RRAM device is trap-controlled space-charge limited conduction, which does not change during the endurance test. As the number of resistive switching (RS) cycles increases, the current in the low-resistance state (LRS) does not change significantly. In contrast, degradation in the high-resistance state (HRS) is noticeably evident. According to the RS cycle, the current shift fits well with the stretched-exponential equation. The normalized noise power spectral density (S_i/I²) measured in the HRS is an order of magnitude higher than that in the LRS owing to the difference in the degree of trap occupancy, which is responsible for the transition of resistance states. During the consecutive RS, the S_i/I² in the HRS rapidly decreases for approximately 100 cycles and then saturates. In contrast, in the LRS, the S_i/I² does not change significantly. Here we propose a model associated with the endurance degradation of the experimental device, and the model is verified with a (Formula presented.) noise measurement.