Modulation of interfacial Schottky barrier of In2Se3/Ti3C2X2 (X = Cl; F; O; OH) ferroelectric heterostructure

Reducing the interface barrier between metals and semiconductors is crucial for designing high-performance optoelectronic devices based on van der Waals heterostructures. In this study, the van der Waals design strategy is employed to investigate the interface contact characteristics in In2Se3/Ti3C2X2 (X=Cl; F; O; OH) ferroelectric heterostructure, which show metal–semiconductor contact characteristics. Under different out-of-plane polarization states of In2Se3, the In2Se3/Ti3C2Cl2 and In2Se3/Ti3C2O2 heterostructures can undergo a transition from Schottky to Ohmic contact. In contrast, the In2Se3/Ti3C2F2 heterostructure transforms from an n-type Schottky contact to a p-type Schottky contact. Notably, the In2Se3/Ti3C2(OH)2 heterostructure forms an Ohmic contact regardless of the polarization direction of In2Se3, with a tunneling probability of 80.75% and 47.78% for the down and up polarization configurations. The results demonstrate that the contact characteristics of ferroelectric heterostructures are jointly governed by the polarization of the ferroelectric layer and the work function of the metal layer. Specifically, when the polarization-induced electric field (Epi) and the built-in electric field (Ebi) arising from charge transfer are oriented in the same directions, their interaction is enhanced; in contrast, when the two fields are aligned in opposite directions, this interaction is attenuated. Meanwhile, despite the presence of a strong Fermi level pinning effect, this pinning actually results in the formation of an Ohmic contact. Therefore, the results indicate that the In2Se3/Ti3C2X2 (X=Cl; F; O; OH) ferroelectric heterostructure has excellent properties and can provide theoretical guidance for experiments.