Surface Defines the Properties: Colloidal Bi2Se3 Nanosheets with High Electrical Conductivity

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 mu m, 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.

Automated summary

The colloidal synthesis of Bi2Se3 nanosheets in ethylene glycol successfully increased their lateral dimensions while keeping thickness within a few nanometers. Sulfuric acid was found to promote lateral growth up to 10 μm, while thickness remained in the range of 10-12 nm. Size-selective precipitation further optimized lateral size distribution for individual contacting of nanosheets, revealing metal-like temperature dependence of resistivity and specific conductivity values.