Theoretical Research On Silicene-based Heterojunction Optoelectronic Materials And Devices

With the development of modern industry,the integrated circuit industry is undergoing a transition from microelectronics to the atomic scale era.Mankind has an increasing demand for small and high-performance semiconductor devices.Twodimensional atomic crystal materials have attracted great interest due to their ultra-thin atomic geometry,rich physical properties and diverse technical applications.For the current industry,most components and equipment are based on silicon.This fact has prompted researchers to study two-dimensional silicon materials,namely silicene,because they can be well matched with current silicon-based devices and components.In this paper,through the establishment of Silicene-based heterojunctions,theoretical predictions of its optoelectronic properties,magnetic properties,etc.,have a theoretical guiding role for the design of new micro-nano electronic devices in the future.In this paper,first-principles calculations study the electronic properties of independent silicene,independent La₂O₃ and Silicene/La₂O₃ heterojunctions.Independent silicene,independent La₂O₃ and Silicene/La₂O₃ heterojunctions all have thermodynamic stability at room temperature.Silicene is a zero-band gap semiconductor.The band structure contains a Dirac cone formed by the linear intersection of ? and ?*bands at the Fermi level.Independent La₂O₃ is an insulator with a large band gap of 5.434 eV.The Silicene/La-La₂O₃ heterojunction exhibits a band gap of 1.753 eV,which is required for Silicene-based semiconductor devices.In addition,the influence of biaxial strain and external electric field on the band structure of Silicene/La₂O₃ heterojunction is also studied,and it is found that biaxial strain and external electric field can effectively modulate the band gap value of Silicene/La₂O₃ heterojunction.These research results indicate the potential application prospects of Silicene-based field effect transistors with La₂O₃ gate dielectric in nanodevices.The NiI₂ single layer is a ferromagnetic semiconductor with a band gap of 2.403 eV Nil2 single layer also has a small dissociation energy and strong in-plane stiffness,which is easy to peel off and maintain an independent planar structure.In this paper,using first-principles calculations,we have calculated the electronic and magnetic properties of silicene monolayer,NiI₂ monolayer and Silicene/NiI₂ van der Waals heterojunction.Silicene monolayer,NiI₂ monolayer and Silicone/NiI₂ van der Waals heterostructures all have thermodynamic stability at room temperature.The NiI₂ monolayer is an indirect bandgap semiconductor with two spin channels,the ground state is a ferromagnetic state,and the magnetic moment is 2 ?B.The band structure of the Silicene/NiI₂ van der Waals heterostructure opens the spin-dependent band gap,maintains the characteristics of the linear Dirac cone dispersion relationship in silicene,and overcomes the lack of inherent band gap in silicene applications.Since the interface between silicene and NiI₂ single layer is close,the magnetization in silicene can be induced.The Silicene/NiI₂ van der Waals heterostructure has perpendicular magnetic anisotropy,which can achieve high density and high thermal stability of magnetic memory.In addition,an electric field is also used to adjust the electronic and magnetic properties of the Silicene/NiI₂ van der Waals heterojunction.Interestingly,under a negative electric field of-0.2 V/A,the direction of spin splitting at the minimum conduction band changes.The Silicene/NiI₂ van der Waals heterojunction,as a twodimensional ferromagnetic semiconductor,plays an important role in the application of spintronics,information storage and storage devices.The theoretical research on Silicene-based heterojunctions in this paper has potential applications in future Silicene-based field effect transistors and new selfselected field effect transistors,and provides certain theoretical guidance for the design of new nanoelectronic devices in the future.