Controlled Construction of Atomic Point Contact with 16 Quantized Conductance States in Oxide Resistive Switching Memory

A resistive switching device with controlled formation and evolution of conductive filament possesses great capability of being miniaturized to atomic scale for the construction of high-density memory arrays and even in-memory computing architectures. Although the switching mechanism based on ion migration and electrochemistry has been clarified, precise control of the evolution dynamics is still a challenge that hinders the direct application of the memory devices. In this contribution, we propose an effective scanning probe microscope tip-assisted approach for the performance modulation of oxide-based resistive switching devices. The directional migration of oxygen anions inside the hafnium oxide nanofilm is regulated by using the voltage-biased scanning probe microscope (SPM) tip as a microelectrode, so that a single filament would be formed deliberately inside the switching matrix to greatly improve the stability and reliability of the memory device. The variations of the switching parameters, e.g. programming voltages and ON/OFF resistances, have been reduced by at least 33%. More importantly, the elaborate tuning of the filament dimension also gives rise to single atomic point contact in the resistive switching device, producing at least 16 half-integer multiples of quantized conductance states that can be used for multilevel data storage and high-order neuromorphic computing paradigm.