van der Waals grain boundaries with inert electrical behaviors in inorganic molecular dielectric film

Grain boundaries (GBs) in insulating crystal films generally create lattice reconstruction and excess mid-gap states, which may form the transport pathways of charge carriers and lead to serious degradation of insulating properties. Here, we reveal the inert electrical behaviors of GBs in polycrystalline inorganic molecular dielectric film attributed to its special van der Waals structure. Temperature-dependent electrical measurements and first-principles calculations uncovered that such GBs are free of mid-gap states, which explains the unexpectedly low leakage current of Sb₂O₃ polycrystalline thin film. Through systematic measurements by conductive atomic force microscopy, we further verify the undistinguishable electrical behaviors within grains and at GBs of the polycrystalline film. Our findings may lay a solid foundation for the applications of inorganic molecular film as a compatible gate dielectric in advanced two-dimensional devices.