Domain nucleation kinetics and polarization-texture-dependent electronic properties in two-dimensional α-In2Se3 ferroelectrics

Abstract

Two-dimensional (2D) ferroelectric semiconductors, such as α-In₂Se₃ with switchable spontaneous polarization and superior optoelectronic properties, exhibit large potential for functional device applications. The electric transport properties and device performance of 2D α-In₂Se₃ are strongly sensitive to the ferroelectric domain structures and polarization textures, but they are rarely explored at the atomic scale. Herein, by a combination of first-principles calculations and a developed domain switching theory, we report the domain nucleation kinetics and polarization-texture dependent electronic properties in α-In₂Se₃ ferroelectrics. Our calculated results reveal that the reversed domains characterized by armchair boundaries tend to form triangular or stripped shape. The energy barrier for propagating domain boundaries is ∼1.42 eV and can be reduced by loading external electric field, which is responsible for driving the evolution of domain structures. Moreover, the domain switching leads to notable changes in the band gap and carrier spatial distribution of α-In₂Se₃ monolayer, resulting in higher electric resistance of multi-polarization domain structures than that of single-polarization state. The domain structures of multilayer α-In₂Se₃ follow a layer-by-layer switching mechanism, which causes the transition of electronic structures from self-doped p–n junctions to type-II semiconductor homojunctions. This study not only provides an in-depth insight into the domain switching mechanisms of α-In₂Se₃ but also opens up the possibility to tailor their electronic and transport properties.