Controlled vapour-phase deposition synthesis and growth mechanism of Bi₂Te₃ nanostructures

This work presents a study on the controlled growth and the growth mechanism of vapour-phase deposited two-dimensional Bi₂Te₃ nanostructures by investigating the influence of growth conditions on the morphology of Bi₂Te₃ nanostructures. The formation of a hexagonal plate geometry for Bi₂Te₃ nanostructures is a consequence of the large difference in growth rate between crystal facets along 〈0001〉 and 〈11$2¯$0〉 directions. Under low Ar carrier gas flow rates (60–100 sccm), the growth of Bi₂Te₃ nanoplates occurs in the mass-transport limited regime, whereas under high carrier gas flow rates (130 sccm), the growth of Bi₂Te₃ nanoplates is in the surface-reaction limited regime. This leads to an increase in the lateral size of Bi₂Te₃ nanoplates with increasing the Ar carrier gas flow rate from 60 to 100 sccm, and a decrease in size for a flow rate of 130 sccm. In addition, the lateral size of Bi₂Te₃ nanoplates was found to increase with increasing growth time due to the kinetic characteristics of material growth. The proposed growth model provides an effective guide for achieving controlled growth of Bi₂Te₃ nanoplates, as well as other two dimensional nanomaterials.