In-Situ Chemical Thinning and Surface Doping of Layered BiSe.

As a promising topological insulator, two-dimensional (2D) bismuth selenide (BiSe) attracts extensive research interest. Controllable surface doping of layered BiSe becomes a crucial issue for the relevant applications. Here, we propose an efficient method for the chemical thinning and surface doping of layered BiSe, forming Se/BiSe heterostructures with tunable thickness ranging from a few nanometers to hundreds of nanometers. The thickness can be regulated by varying the reaction time and large-size few-layer BiSe sheets can be obtained. Different from previous liquid-exfoliation methods that require complex reaction process, in-situ and thickness-controllable exfoliation of large-size layered BiSe can be realized via the developed method. Additionally, the formation of Se nanomeshes coated on the BiSe sheets remarkably enhance the intensity of Raman vibration peaks, indicating that this method can be used for surface-enhanced Raman scattering. The proposed chemical thinning and surface-doping method is expected to be extended to other bulk-layered materials for high-efficient preparation of 2D heterostructures.