Prediction of intrinsic two-dimensional ferroelectrics in In2Se3 and other III2-VI3 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 In2Se3 and other III2-VI3 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 In2Se3/graphene, exhibiting a tunable Schottky barrier, and In2Se3/WSe2, 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.

Van der Waals Contact to 2D Semiconductors with a Switchable Electric Dipole: Achieving Both n‐ and p‐Type Ohmic Contacts to Metals with a Wide Range of Work Functions

“…We note that the change of contact from (001) to (00‐1) surface may need reverse the pS, but could be also achieved through switching the ferroelectric polarization for ferroelectrics by an external electric field 7. In the Al 2 Se 3 ‐Mo 2 CF 2 junction, Φ n (ML − A) is much smaller than Φ p (ML − A) and Φ n (ML − B) is much larger than Φ p (ML − B) from our calculation at both PBE and HSE06 levels (Figures S5 and S6, Supporting Information).…”

“…Their potential applications in different fields have been demonstrated. The first class of 2D pS is group III 2 ‐VI 3 ferroelectrics (M 2 X 3 , M = Al, Ga, In; X = S, Se, Te),7,8 and some of them have been synthesized in experiment 4,9–13. Particularly, ferroelectric In 2 Se 3 had been applied to data storage with the switchable polarization, spintronics,9 and visible light absorption 10,14–17.…”

Progress and prospects in low‐dimensional multiferroic materials

“…Another class of stable single‐layer vdW 2D FE materials rooted in III 2 –VI 3 such as In 2 Se 3 has been proposed theoretically by Ding et al that exhibits room temperature ferroelectricity with reversible spontaneous electric polarization in both out‐of‐plane and in‐plane orientations . Proper integration of these materials with other classes of 2D systems is expected to substantially broaden the tunability and device potential of vdW heterostructures.…”

Design of Single‐Molecule Multiferroics for Efficient Ultrahigh‐Density Nonvolatile Memories

“…In most cases of MRAMs, the energy cost depends mostly on the first term J for the exchange interaction of adjacent spins, which will be much reduced upon prolonged spin-spin distance (e.g., in diluted magnetic semiconductors [1] ) or when the number of adjacent spins N is reduced in low-dimensions. For example, ferroelectricity (FE) has been recently explored in many 2D materials and revealed to be robust at ambient conditions, [2][3][4][5][6][7][8][9][10][11][12][13][14][15] as summarized in our recent review. As a result, a high Curie temperature can still be maintained when the number of adjacent dipoles is reduced.…”