We present resistive switching (RS) behavior of few-layer hexagonal boron nitride (h-BN) mediated by defects and interfacial charge transfer. Few-layer h-BN is grown by metal-organic chemical vapor deposition and used as active RS medium in Ti/h-BN/Au structure, exhibiting clear bipolar RS behavior and fast switching characteristics about ∼25 ns without an initial electroforming process. Systematic investigation on microstructural and chemical characteristics of the h-BN reveals that there are structural defects such as homoelemental B-B bonds at grain boundaries and nitrogen vacancies, which can provide preferential pathways for the penetration of Tix+ ions through the h-BN film. In addition, the interfacial charge transfer from Ti to the h-BN is observed by in situ X-ray photoelectron spectroscopy. We suggest that the attractive Coulomb interaction between positively charged Tix+ ions and the negatively charged h-BN surface as a result of the interfacial charge transfer facilitates the migration of Tix+ ions at the Ti/h-BN interface, leading to the facile formation of conductive filaments. We believe that these findings can improve our understanding of the fundamental mechanisms involved in RS behavior of h-BN and contribute a significant step for the future development of h-BN-based nonvolatile memory applications.
Keywords: MOCVD; RRAM; h-BN; interfacial charge transfer; resistive switching; structural defect.