Prediction of intrinsic two-dimensional ferroelectrics in In ₂Se ₃ and other III ₂-VI ₃ van der Waals materials

Abstract

Interest in two-dimensional (2D) van der Waals materials has grown rapidly across multiple scientific and engineering disciplines in recent years. However, ferroelectricity, the presence of a spontaneous electric polarization, which is important in many practical applications, has rarely been reported in such materials so far. Here we employ first-principles calculations to discover a branch of the 2D materials family, based on In ₂Se ₃ and other III ₂-VI ₃ van der Waals materials, that exhibits room-temperature ferroelectricity with reversible spontaneous electric polarization in both out-of-plane and in-plane orientations. The device potential of these 2D ferroelectric materials is further demonstrated using the examples of van der Waals heterostructures of In ₂Se ₃/graphene, exhibiting a tunable Schottky barrier, and In ₂Se ₃/WSe ₂, showing a significant band gap reduction in the combined system. These findings promise to substantially broaden the tunability of van der Waals heterostructures for a wide range of applications.

Abstract

The development of devices based on 2D materials beyond graphene benefits from identifying compounds with diverse functional properties. Here, the authors predict computationally that 2D In ₂Se ₃ and related materials are room temperature ferroelectrics with both in- and out-of-plane polarization.