Defect-mediated resistive switching in thin multilayer hexagonal boron nitride: A first principles study of charge state modulation

Abstract

Among the two-dimensional materials, hexagonal boron nitride (h-BN) has recently attracted much attention for resistive switching applications. The majority of the prior works focused on the switching mechanisms, which involve the diffusion of metal ions from the electrode into the boron vacancies (V_B). Nonetheless, in such multi-layer systems, removing these metal ions during the RESET process is difficult and results in device failure. In this work, we explored resistive switching in h-BN, focusing on V_B and Stone-Wales (SW) defects. SW defects act as simplified model for atomic rearrangements at grain boundaries. Our study investigate how these defects behave across different charge states, shedding light on their role in resistive switching mechanisms. The results of our Density Functional Theory (DFT) calculations showed the feasibility of SET and RESET operations in thin h-BN layers without the presence of metal atoms. We employed Nudged Elastic Band (NEB) calculations to show that SW defects greatly reduce the energy barrier for boron diffusion between h-BN layers and facilitates the formation of conductive bridges. These bridges, which are essential for SET and RESET processes, form and break dynamically in response to changes in charge states, particularly under the influence of negative charges. The stability of these conductive bridges was evaluated using ab initio Molecular Dynamic (AIMD) simulations. Moreover, electronic transport calculations performed using non-equilibrium Green's function (NEGF) revealed an I_on/I_off ratio of 10³. Our findings show that the combination of V_B and SW defects is sufficient to enable resistive switching, making thin multilayer h-BN a promising candidate for threshold switching memristors.