Impurity-Controlled Crystal Growth in Low-Dimensional\nBismuth Telluride

Topological\ninsulators, such as layered Bi2Te3, exhibit\nextraordinary properties, manifesting profoundly only at\nnanoscale thicknesses. However, it has been challenging to synthesize\nthese structures with controlled thicknesses. Here, control over the\nthickness of solvothermally grown Bi2Te3 nanosheets\nis demonstrated by manipulating the crystal growth through select\nand controlled impurity atom addition. By a comprehensive analysis\nof the growth mechanism and intentional addition of Fe impurity, we\ndemonstrate that the nucleation and growth of few-layer nanosheets\nof Bi2Te3 can be stabilized in solution. Via\noptimization of the Fe concentration, nanosheets thinner than 6 nm,\nand as thin as 2 nm, can be synthesized. Such thicknesses are smaller\nthan the anticipated critical thickness for the transition of topological\ninsulators to the quantum spin Hall regime.