Ferroelectric Control of Band Alignments in In2Se3/h-BN and CuInP2S6/h-BN van der Waals Heterostructures

Recently, 2D ferroelectric (FE) heterostructures have become a subject of great interest due to their potential device applications and the underlying physics involved. In this study, the first-principles calculations are employed to examine the FE control of electronic structures in 2D FE heterostructures, specifically In2Se3/h-BN and CuInP2S6 (CIPS)/h-BN. In these results, it is demonstrated that by reversing the polarization of the FE layers, the band alignment of the heterostructures can be interconverted between type II and type I. For In2Se3/h-BN, the variation of out-of-plane polarization can be attributed to the hindrance and facilitation of charge transfer from h-BN to In2Se3 by the intrinsic electric field of the In2Se3 monolayer. For CIPS/h-BN heterostructures, the higher transferred charge in the C-dn configuration due to the presence of built-in electric fields and the stronger interfacial interaction in the C-dn configuration result in a higher polarization value compared to the C-dn configuration. Moreover, the carrier mobility of the heterostructures can also be effectively modulated by the FE polarization. In these findings, the potential significance of FE heterostructures with tunable band alignment and bandgap is highlighted in the development of nanoscale optoelectronic devices.