Interfacial‐Modulated Growth of Nanostructured Bi₂Te₃ Films for Enhancing Thermoelectric Performance

Abstract

Little room remains for further reducing lattice thermal conductivity (κL) which cannot be reduced below the amorphous limit. Further improvements in the thermoelectric (TE) figure of merit should rely on enhancing the TE power factor (PF) with low electrical thermal conductivity (κe). Layered Bi2Te3 exhibits anisotropic TE properties and modulation of its growth behavior can effectively modify the transport of electrons and phonons and thus enhance its TE properties. Herein, Bi2Te3 films are grown by molecular beam epitaxy with the modulation of substrates, seed layer, and thickness. The nanopillars‐dominated film without seed layer changes to nanoplates dominated after the seed layer is predeposited, and the grain size ratio of the (006)/(015) plane increases. The room temperature PF of the stoichiometric Bi2Te3 grown on SiO2 with seed layer reaches 34 μW cm−1 K−2 with a low κe of 0.39 W m−1 K−1. This strategy can be applied in other layered materials with specific growth behavior and properties for nano–micro devices.