Synthesis and Properties of Bismuth Selenide Based Nanolaminates for Application in Thermoelectrics

In this work, simple and cost-effective phyiscal vapor deposition method is applied for deposition of single Bi₂Se₃, Bi_1.925Sn_0.075Se₃, Bi₂Se_2.975Te_0.025 ultrathin films of average thickness 10–12 nm, and for the fabrication of n-type 5-layer nanolaminates. The nanolaminates are composed from alternating doped and undoped ultrathin films. Electrical and thermoelectric properties (Seebeck coefficient, resistivity, electron thermal conductivity, charge carrier concentration, and mobility) of nanolaminates as well as single ultrathin undoped and doped films are studied at room temperature under ambient conditions. Both types of nanolaminates show 75–125% increase of the Seebeck coefficient accompanied by the 65–85% reduction of the electron thermal conductivity in comparison with the nanostructured bulk materials of similar chemical compositions. The mechanisms underlying such improvement of properties of studied nanolaminates in comparison with the nanostructured bulk counterparts are discussed.