Nonvolatile resistance switching in <i>h</i>-BN by van der Waals ferroelectric engineering

The metallization of hexagonal boron nitride (h-BN) monolayer with a wide bandgap is crucial for unlocking its potential in various fields. Although carrier doping is the most straightforward way for achieving metallization, and it can be realized by interlayer charge transfer in a van der Waals (vdW) heterostructure constructed with another two-dimensional material, current attempts such as graphene/h-BN and α-In2Se3/h-BN vdW heterostructures fail in the h-BN metallization. In this work, a vdW heterostructure of graphene/α-In2Se3/h− BN is proposed. Interestingly, with the negative (positive) charge side of α-In2Se3 interfacing with h-BN (graphene), the polarization field of α-In2Se3 pushes the valence band of h-BN to higher energy and the Dirac point of graphene to lower energy so that charge transfer mediated by α-In2Se3 from h-BN to graphene becomes possible, driving h-BN to be metallic. In contrast, with the reversal of the ferroelectric polarization of α-In2Se3, no charge transfer from or to h-BN is allowed, and h-BN recovers its insulating feature. The nonvolatile resistance switching of h-BN by the graphene/In2Se3/h-BN vdW heterostructure will promote its practical applications, such as memory devices.