Abstract
The optical response of semiconducting materials is dominated by exciton which is a bound state of an electron and a hole attracted to each other by Coulomb interaction. When the thickness of the material is comparable to atomic level, strong suppression of Coulomb screening effect leads to rather high exciton binding energy and some other interesting phenomenon. Therefore, we have to study on the heterostructure or the interface since this kind of two-dimensional material cannot exist on its own. Apart from the change of Coulomb screening effect, when it comes to heterstructure or the interface, the intrinsic electrical field which is perpendicular to the interface will be generated due to the different work function of different materials. The breakdown of inversion symmetry owing to this electrical field will lead to nonzero berry curvatures. Then, nearly all properties of materials need corrections. For example, the charge transfer between will make our material to be n-doped or p-doped, which will largely increase the conductance of the material, or maybe make the material go through a phase transition. Another example is about the spintronics. This kind of inversion symmetry will lead to stronger spin relaxation to some extent which means shorter spin lifetime and that is bad for spintronics. Therefore, study on heterstructure or interface is necessary and will help us manipulate the properties of the materials to make it more convenient to be applied.
Anyone interested is welcome to attend.