Solvothermal synthesis of crystalline 2D bismuth telluride with an isoelectronic dopant

Abstract

In this work, we present a solvothermal, in situ doping methodology for synthesizing crystalline doped 2D bismuth telluride (Bi2Te3) nanoplates. Isoelectronic antimony (Sb) substitution at the bismuth (Bi) site is chosen to minimize the lattice strain in the nanostructure. Using a combination of x-ray techniques and electron microscopy, we demonstrate that the rhombohedral crystal structure (space group R3̄m), characteristic of Bi2Te3 is preserved in few-quintuple-layer, hexagonal nanoplates. Our findings reveal a uniform dispersion of Sb within the nanoplates up to an atomic concentration of 1%. Beyond this threshold, a disordered SbTe alloy begins to form along the crystal edges in addition to Sb substitution at the Bi sites in the bulk, restricting further growth of the nanoplates. In addition, we examine the different stresses that develop within the nanoplates as lattice strain increases due to Sb substitution. This study provides fundamental insights into the dopant’s effect on the self-assembled growth of electronically relevant 2D crystals.