In this work, a simple cost-effective physical vapor deposition method for obtaining high-quality Bi 2 Se 3 and Sb 2 Te 3 ultrathin films with thicknesses down to 5 nm on mica, fused quartz, and monolayer graphene substrates is reported. Physical vapor deposition of continuous Sb 2 Te 3 ultrathin films with thicknesses 10 nm and below is demonstrated for the first time. Studies of thermoelectrical properties of synthesized Bi 2 Se 3 ultrathin films deposited on mica indicated opening of a hybridization gap in Bi 2 Se 3 ultrathin films with thicknesses below 6 nm. Both Bi 2 Se 3 and Sb 2 Te 3 ultrathin films showed the Seebeck coefficient and thermoelectrical power factors comparable with the parameters obtained for the highquality thin films grown by the molecular beam epitaxy method. Performance of the best Bi 2 Se 3 and Sb 2 Te 3 ultrathin films is tested in the two-leg prototype of a thermoelectric generator.
The majority of proposed exotic applications employing 3D topological insulators require high-quality materials with reduced dimensions. Catalyst-free, PVD-grown Bi2Se3 nanoribbons are particularly promising for these applications due to the extraordinarily high mobility of their surface Dirac states, and low bulk carrier densities. However, these materials are prone to the formation of surface accumulation layers; therefore, the implementation of surface encapsulation layers and the choice of appropriate dielectrics for building gate-tunable devices are important. In this work, all-around ZnO-encapsulated nanoribbons are investigated. Gate-dependent magnetotransport measurements show improved charge transport characteristics as reduced nanoribbon/substrate interface carrier densities compared to the values obtained for the as-grown nanoribbons on SiO2 substrates.
In this work, simple and cost‐effective phyiscal vapor deposition method is applied for deposition of single Bi2Se3, Bi1.925Sn0.075Se3, Bi2Se2.975Te0.025 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.
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