Two-dimensional materials have been widely investigated to implement memristive devices for data storage or neuromorphic computing applications because of their ultra-scaled thicknesses and clean interfaces. For example, resistance switching in hexagonal boron nitride (h-BN) has been demonstrated. This mechanism is most of the time attributed to the movement of metallic ions. It has however also been reported when h-BN is contacted with two inert electrodes such as graphene or Pt. We suggest here that the switching mechanism of the latter devices, which has not yet been clearly established, relies on locals change of the electronic structure of h-BN as caused by atomic defects, e.g., multi-vacancies. This class of intrinsic h-BN defects can create electrically controllable interlayer bridges. We use a combination of hybrid density functional theory and the Non-equilibrium Green’s function formalism to show that a single interlayer bridge resulting from the presence of a trivacancy in a graphene/h-BN/graphene stack leads to a switching voltage of ~5 V and a high-to-low resistance ratio >100. Both values lie within the reported experimental range and thus confirm the likelihood that intrinsic defects play a key role in the resistance switching of h-BN in contact with inert electrodes.

The resistance state of filamentary memristors can be tuned by relocating only a few atoms at interatomic distances in the active region of a conducting filament. Thereby the technology holds promise not only in its ultimate downscaling potential and energy efficiency but also in unprecedented speed. Yet, the breakthrough in high‐frequency applications still requires the clarification of the dominant mechanisms and inherent limitations of ultra‐fast resistive switching. Here bipolar, multilevel resistive switchings are investigated in tantalum pentoxide based memristors with picosecond time resolution. Cyclic resistive switching operation due to 20 ps long voltage pulses of alternating polarity are experimentally demonstrated. The analysis of the real‐time response of the memristor reveals that the set switching can take place at the picosecond time‐scale where it is only compromised by the bandwidth limitations of the experimental setup. In contrast, the completion of the reset transitions significantly exceeds the duration of the ultra‐short voltage bias, demonstrating the dominant role of thermal diffusion and underlining the importance of dedicated thermal engineering for future high‐frequency memristor circuit applications.

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