Self-formation of thickness tunable Bi2Te3 nanoplates on thin films with enhanced thermoelectric performance

Abstract

Bismuth telluride thin films were prepared on flexible substrates by magnetron sputtering and then annealed at different temperatures. Interestingly, single-crystal Bi₂Te₃ nanoplates emerged on the thin films spontaneously, free of any template or catalyst. The self-formation of nanoplates could be ascribed to thermal stress, and a physical mechanism was proposed accordingly. Thermoelectric measurements illustrated that the electronic conductivity increased with annealing temperature owing to the gradually improved crystallization, but the thermal conductivity decreased as a result of enhanced scattering by the lamellar structure. This improved the figure of merit ZT of the Bi₂Te₃ thin films by more than 4 times and provided us a new concept to obtain high-performance thermoelectric materials.