Electronic And Optical Properties Of 2D Black Phosphorus And In Se Under External Field Modulation

Two-dimensional(2D)materials are one of the important research areas in condensed matter physics.Monolayer black phosphorus(phosphorene)and monolayer indium selenide(In Se),as other popular 2D materials,are promising for a wide range of applications and have high research potential.The study of thin films,nanoribbons and quantum dots(QDs)of phosphorene materials has been reported,but the study of quantum ring(QR)structure is still at an early stage.Meanwhile,the previous literatures have neglected the electron-electron interaction,while in our study we complements this gap.For monolayer In Se materials,the related monolayer and few layers structures have also been reported,but the study of QD structures has not yet been fully researched.Our theoretical results hope to lead to further studies on this material.This paper,consists of five chapters,focuses on the electrical and optical properties of phosphorene and monolayer In Se.We theoretically investigate the energy band structures,Landau energy levels and magneto-optical properties of phosphorene and monolayer In Se films and their corresponding quantum dots using the tight-binding method(Hubbard method)and the k?p method.For the phosphorene materials,the results show that:(1)the energy gap and edge state bands of the phosphorene QR structure can be effectively controlled by the size of the hole inside the ring,the applied electric and magnetic fields.(2)All edge states are only provided by phosphorus atoms with outer and inner zigzag boundaries.(3)Edge states induced by the inner and outer boundaries all exhibit different response behaviors to electric and magnetic fields,resulting in different energy spectra with independent modulation capabilities.(4)The external electric field can tune the optical absorption from the edge states to the edge states of the phosphorene QRs.For monolayer In Se materials,the results show that:(1)in the low energy region,the Landau levels of monolayer In Se films exhibit linear dependence and show very different behavior in the valence and conduction bands.The Landau levels exhibit a distinctly non-linear Hofstadter butterfly spectrum in the high energy region.(2)The optical absorption spectrum of monolayer In Se indicates that there is no optical absorption at the top of the valence band and the bottom of the conduction band,and the optical gap is significantly larger than the energy gap.(3)Compared with other 2D materials such as phosphorene,monolayer In Se quantum dots exhibit the following distinctive features:(a)The edge states appear at the bottom of the conduction band regardless of the shape of In Se quantum dots.(b)The edge states of the In Se quantum dots are mainly provided by the In atoms located at the armchairtype and zigzag-type edges.(c)The optical gap is different from the energy gap.The QDs with hexagonal and triangular structures produce isotropic absorption spectra,while the rectangular QDs produce anisotropic absorption spectra.And the applied magnetic field would weaken this degree of anisotropy.