Tuning electronic properties of 2D ferroelectric Al2Se3/graphene heterostructure by ferroelectric polarization and electric field

Abstract

Currently, two-dimensional (2D) ferroelectric heterostructures, characterized by their atomic thickness and switchable polarization, exhibit tunable electronic properties and demonstrate promising potential in microelectronics. Here, 2D Al₂Se₃/graphene ferroelectric heterostructures were investigated based on first-principles calculations. The results show that the band structure of heterostructure exhibit a simple superposition of energy bands of the two individual monolayers, indicating a relatively weak van der Waals (vdW) interaction. Notably, the band alignments and surface potential differences of the heterostructures are highly dependent on the polarization orientation of Al₂Se₃. Furthermore, the contact type and barrier height of the heterostructures can be modulated by external electric field (E): For Al₂Se₃/graphene-FE_down structure, a transition from n-type Ohmic contact to n-type Schottky contact and then to p-type Schottky contact can be achieved. For Al₂Se₃/graphene-FE_up structure, a transition from p-type Ohmic contact to p-type Schottky contact and then to n-type Schottky contact is possible under external electric field. Besides, only a small electric field less than 0.1 V/Å can switch the contact type from Ohmic to Schottky contacts. This work can provide physical guidance for designing controllable Schottky nanodevices with high performance.