Transition from weak antilocalization to linear magnetoresistance by tuning structure geometry and chemical potential in nanostructured Bi2Se3 films

We report the electrical and magnetic transport behavior in vertical Cu-doped Bi2Se3 nanoplate films prepared by the chemical vapor deposition method. In vertical Cu-doped Bi2Se3 nanoplate films, the topological surface states are tuned by both the large surface-to-bulk ratio and the Cu doping. Due to their high specific surface area, the magnetoresistance of the vertical undoped Bi2Se3 nanoplate film exhibits a weak antilocalization effect, and it indicates that the topological surface state properties are greatly enhanced. In vertical Cu-doped Bi2Se3 nanoplate films, the electron doping is inhibited, and the carrier type is changed from n-type to p-type. The observed linear magnetoresistance is attributed to have a quantum origin from the topological surface states. When the Cu concentration reaches 1.73 at.% in vertical Bi2Se3 nanoplate film, the linear magnetoresistance can be maintained up to 100 K. Meanwhile, these vertical nanoplate films exhibit the 3D magnetotransport property. Thus, using the same material system with a broad range of carrier density and type, our work shows the transition from a weak-antilocalization to linear magnetoresistance in nanostructured topological insulator Bi2Se3 films with an unusual morphology where the nanoplates are vertically aligned to increase the surface area.