Visualizing interface states in In2Se3-WSe2 monolayer lateral heterostructures

Abstract

Recent findings of two-dimensional (2D) ferroelectric (FE) materials provide more possibilities for the development of 2D FE heterostructure electronic devices based on van der Waals materials and the application of FE devices under the limit of atomic layer thickness. In this paper, we report the in-situ fabrication and probing of electronic structures of In2Se3–WSe2 lateral heterostructures, compared with most vertical FE heterostructures at present. Through molecular beam epitaxy, we fabricated lateral heterostructures with monolayer WSe2 (three atomic layers) and monolayer In2Se3 (five atomic layers). Type-II band alignment was found to exist in either the lateral heterostructure composed of anti-FE β′-In2Se3 and WSe2 or the lateral heterostructure composed of FE β*-In2Se3 and WSe2, and the band offsets could be modulated by ferroelectric polarization. More interestingly, interface states in both lateral heterostructures acted as narrow gap quantum wires, and the band gap of the interface state in the β*-In2Se3–WSe2 heterostructure was smaller than that in the β′-In2Se3 heterostructure. The fabrication of 2D FE heterostructure and the modulation of interface state provide a new platform for the development of FE devices.