The Band Tunning And In-plane Ferroelectric Tunnel Junctions Design Based On The 2D α-In₂Se₃/Ⅳ-Ⅵ Group Semiconductor Heterostructures

The rapid development of information technology has put forward new requirements for information storage.Ferroelectric materials have received extensive attention because they can be used to fabricate high-performance non-volatile memories.Due to the size effect of traditional perovskite-structured ferroelectric materials,it will bring reliability problems in the development and application of high-density ferroelectric memories,thus limiting the development of ferroelectric memories.Since the discovery and extensive research of two-dimensional materials,two-dimensional ferroelectric materials have come into people’s vision.Among them,two-dimensionalα-In₂Se₃ has attracted much attention from scientists because of its correlative in-plane and out-of-plan spontaneous polarizations.Previous studies show that van der Waals heterostructures consist ofα-In₂Se₃ and two-dimensional semiconductors exhibit wide potential in the applications of band tuning and ferroelectric memory and logic devices.However,the related researchs on theα-In₂Se₃/semiconductor ferroelectric heterostructures and electronic devices are still in early state,and their structures and performances need future improvement.Therefore,in this essay,a type of two-dimensional ferroelectric heterostructures was designed by utilizing two-dimensionalα-In₂Se₃ and hexagonal IV-VI semiconductors（Sn Te and Pb Se）.The energy band tuning behaviors of the designed two-dimensionalα-In₂Se₃/semiconductor heterostructures,are studied on systematic first-principles calculations.And we also proposed a type of excellent in-plane ferroelectric tunnel junction based on the designedα-In₂Se₃ ferroelectric heterostructures and studied its electric properties.The results obtained are as follows:（1）Two-dimensionalα-In₂Se₃/semiconductor heterojunction and its energy band tunning.We first designed a type of two-dimensional van der Waals ferroelectric heterostructures by utilizing theα-In₂Se₃ ferroelectric monolayer and hexagonal two-dimensional group IV-VI semiconductors（Sn Te and Pb Se）,The band tuning behaviors as controlled by the ferroelectric polarization ofα-In₂Se₃ was explored based on the optimized ferroelectric heterostructures.It is found that two-dimensionalα-In₂Se₃/group IV-VI semiconductor ferroelectric heterostructures exhibit excellent polarization-controlled band tuning behaviors,with some of them even showing insulating to metallic transition.The band tuing effects of the designedα-In₂Se₃ferroelectric heterostructures are even more significant than that have ever been reported in the literatures,indicating a bright future ofα-In₂Se₃ ferroelectric heterostructures in the application of high-performance ferroelectric devices（2）The design and electrical properties ofα-In₂Se₃/semiconductor in-plane ferroelectric tunnel junctions.Based on the above designed heterostructures and the correlated in-plane and out-of-plane ferroelectric polarizations ofα-In₂Se₃,we proposed a simple structure two-terminal in-plane ferroelectric tunnel junction,in which the ON and OFF states can be controlled by the in-plane applied voltage.Based on the study of transport properties,it is found that the In₂Se₃/Sn Te-based in-plane ferroelectric tunnel junction with the Sn-Se interface exhibit conduction and tunneling transport mechanisms for the ON and OFF states,respectively,leading to an ON/OFF ratio of more than 5×10³.And the ON/OFF ratio is amplified exponentially with increasing the barrier length of the ferroelectric tunnel junction.The above research results have important implicationsin for the design and development of high-performance ferroelectric memories.