First-principles study of phase transition in the α-In₂Se₃/metal heterostructures

Abstract

With the discovery of two-dimensional (2D) ferroelectric materials such as CuInP2S6 and α-In2Se3, the ferroelectric field effect transistors (Fe-FETs) based on these materials have entered a rapid-development period in experiments. The metal/semiconductor contact is an unavoidable topic in the construction of devices. Although previous studies have explored the contact properties in monolayer α-In2Se3/metals heterostructures, the stable structures of heterojunction have not been fully analyzed and discussed. In this paper, heterostructures monolayer α-In2Se3/metals (Pd, Pt, Cu, Ag and Au) are discussed. According to different stacking types, the structures and energy of 160 heterostructures are calculated and compared. When α-In2Se3 contacts with the Pd, Pt and Cu, the α-In2Se3 may transforms into β-In2Se3. This phenomenon has hardly been mentioned or analyzed in previous reports. Contacting with the Au and Ag, the α-In2Se3 maintains the original structure. The internal physical mechanism of phase transition is explained from the binding energy and the charge transfer. The paper provides sufficient theoretical support for research and development of the Fe-FETs based on α-In2Se3.