Mechanical Exfoliation and Electron Transport of Topological Insulator Nanoribbons

Bismuth selenide (Bi$_{2}$Se$_{3}$), a stoichiometric material of a single Dirac-cone band structure, is one of the most promising candidates to realize the topologically non-trivial surface state protected by time reversal symmetry. Especially, many exotic physical phenomena are predicted to emerge in low dimensional nanostructures of Bi$_{2}$Se$_{3}$, such as the crossover between 3D to 2D topological insulator. Due to the weak Van der Waals interaction between adjacent quintuple layers (QLs), Bi$_{2}$Se$_{3}$ can be exfoliated down to a few QLs. We will present the mechanical exfoliation of topological insulator nanoribbons by an atomic force microscope (AFM) tip, which enables ultra-thin topological insulator down to a single QL. Electron transport measurement on low dimensional topological insulator will be also discussed, as well as the conductivity mapping experiment using a microwave scanning probe technique.