Bottom‐Electrode Nanoasperities as a Root of the High‐Performance Resistive‐Switching Effect

Resistive random access memory (ReRAM) has attracted considerable attention for next‐generation nonvolatile microelectronic memory because of its advantages, including scalability and fast switching speed. Many different parameters of memory cells contribute to their performance; specifically, the functional dielectric layer and its stoichiometry, interface layers, temperature treatment, etc., have significant influence on the operating voltages, power consumption, and endurance. This study experimentally demonstrates that such a simple property of a ReRAM cell as the nanomorphology of the bottom electrode drastically affects the device performance. Tantalum‐oxide‐based memory cells containing nanoasperities at the electrode surface exhibit a forming‐free resistive‐switching effect with low operating voltage (less than 1.2 V) and an endurance of ≈107 cycles, whereas identical structures with a flat bottom electrode do not exhibit the resistive‐switching effect at all. Conductive atomic force microscopy over the memory cells reveals that the conductive nanofilaments are localized above the nanoasperities. This experimental result is in accordance with the local enhancement of the electric field by 200% predicted by the simulation of the electric field across Ta2O5 functional layer using the particular nanoasperities’ cross section. Therefore, the usage of such nanoasperities offers great potential for control over the forming process and performance in resistive‐switching devices. It is demonstrated that such a simple property of a ReRAM cell as the nanomorphology of the bottom electrode drastically affects the device performance. Memory cells containing nanoasperities at the electrode surface exhibit a high‐performance resistive‐switching effect in contrast to structures with a flat bottom electrode.