Charge carrier distribution in the region of charged domain walls in reduced lithium niobate

Charged domain walls (CDWs) in ferroelectric materials are of interest from both fundamental and applied perspectives due to their unique electrophysical properties, which differ significantly from those of the bulk material. Until recently, research efforts primarily focused on studying these properties, while less attention was given to the finite-thickness regions of CDWs with heterogeneous electrical conductivity. This study proposes a model describing the charge carrier distribution within the conductive region of CDWs. The dependencies of charge carrier concentration and mobility on the distance from the CDW were determined. An analytical expression for current-voltage characteristics, measurable by conductive atomic force microscopy (c-AFM), was also proposed. The model has been experimentally validated using AFM methods. In particular, the Debye screening length of the electric field of head-to-head (H–H) CDWs by free charge carriers in strongly reduced LiNbO 3 crystals was found to be 90±10 nm. Additionally, the values of mobility and concentration of polarons forming the conductive H–H CDW were determined. The bound polaron concentration in this region is estimated to be approximately 30 times greater than in the monodomain region, reaching ≈3.8·10 17 cm -3 .