The Transport Properties Of Silicene Nanoribbons

Silicene is a novel two-dimensional Dirac material that is morphologically a singlecrystal lattice of silicon atoms.Silicene has a hexagonal honeycomb structure similar to that of graphene,and its low energy excitation is also a massless Dirac fermion.From theoretical proof to experimental preparation,the development of silicene was only a few decades,but due to its unique structure and characteristics,it has now become a hot research direction in the field of silicon-based materials,condensed matter physics,chemistry and even electronic information.Silicene is similar in structure to graphene and has almost all the peculiar quantum effects of graphene.Unlike graphene,silicene has a special low-buckled structure that makes it possible for the silicene to support relatively large spin-orbit coupling and to open an 1.55 me V band-gap at the Dirac points K and K?.Compared with graphene,the compatibility of silicene with the current mature silicon-based semiconductor process is even better.Therefore,it may have a wide range of potential applications in the future fields of spintronics and nanoelectronics.It has been found that the application of a vertical electric field can be used to control the band-gap of the silicene and cause a topological phase change as the electric field increases.The compatibility of silicene with silicon-based technology has inspired many interesting studies,such as spin-and valley-Hall effect,quantum anomalous Hall effect,valley-spin coupling and so on.In this paper,we investigate the strain control of silicene heterojunctions and achieve spin separation.We hope to establish a larger band-gap and spin-orbit coupling in the silicene to achieve the disulfide-like valley electronic devices effect.We mainly do the following research:(1)The band separation of the silicene was observed under the combined effect of strain and electric field;(2)Applying strain to the silicene heterojunctions to see the change in transport properties;(3)Applying strain on the silicene to see changes in the nature of the valley transport;(4)The spin polarization is adjusted by changing the strain angle.Although the experimental preparation of silicene on metal substrates has been achieved,the process is still relatively complex,so the current main research approach is the use of computer simulation.Silicene nanoribbons,as an important part of the study on the properties of silicene,have a great effect on the research of new materials and have extremely important scientific value.In our research,we mainly use the theory of transition between semiconductors and the low-energy effective Hamiltonian model in the tight-binding approximation.In this paper,the main four parts of the study on the photoelectric properties and electron transport properties of silicene and their application of electromagnetic fields are discussed:(1)Firstly,a uniform center-symmetric depression of both ends of the nanoribbons was fabricated and a wide-narrow-wide hollow nanoribbons model was constructed.The energy band diagram of the three regions was obtained by simulation.(2)The transmission spectrum of the hollow nanoribbons was simulated by means of Green's function;(3)Analysis of the change of the applied electric and magnetic field characteristics of the whole system;(4)Adjust the width of the narrow area to see the change of the transmission spectrum.