Surface Defines the Properties: Colloidal Bi<sub>2</sub>Se<sub>3</sub> Nanosheets with High Electrical Conductivity
Christoph Bauer, Rostyslav Lesyuk, M. Samadi Khoshkhoo, Christian Klinke, Vladimir Lesnyak, Alexander Eychmüller
Abstract
We investigated the colloidal synthesis of Bi2Se3 nanosheets in ethylene glycol with the goal of increasing their lateral dimensions while keeping their thickness within a few nanometers. The influence of proton-donating sulfuric acid was found to be a triggering factor that promoted the lateral growth of up to 10 μm, whereas the thickness remained in the range 10–12 nm. The lateral size distribution was further optimized by size-selective precipitation enabling individual contacting of the nanosheets by electron-beam lithography. Electrical characterization of individually contacted nanosheets revealed a metal-like temperature dependence of the resistivity and values of the specific conductivity in the range of 470 S/cm at room temperature and 880 S/cm at 5.5 K, which is attributed to the surface-induced off-stoichiometry. The presented colloidal nanosheets can potentially serve as a platform for further studies on topologically nontrivial surface states and arising quantum phenomena in two-dimensional systems.