Thickness-dependent properties of ultrathin bismuth and antimony chalcogenide films formed by physical vapor deposition and their application in thermoelectric generators

In this work, a simple cost-effective physical vapor deposition method for obtaining high-quality Bi2Se3 and Sb2Te3 ultrathin films with thicknesses down to 5 nm on mica, fused quartz, and monolayer graphene substrates is reported. Physical vapor deposition of continuous Sb2Te3 ultrathin films with thicknesses 10 nm and below is demonstrated for the first time. Studies of thermoelectrical properties of synthesized Bi2Se3 ultrathin films deposited on mica indicated opening of a hybridization gap in Bi2Se3 ultrathin films with thicknesses below 6 nm. Both Bi2Se3 and Sb2Te3 ultrathin films showed the Seebeck coefficient and thermoelectrical power factors comparable with the parameters obtained for the high-quality thin films grown by the molecular beam epitaxy method. Performance of the best Bi2Se3 and Sb2Te3 ultrathin films is tested in the two-leg prototype of a thermoelectric generator. [Display omitted] •5–10 nm thin Bi2Se3 and Sb2Te3 films were synthesized by physical vapor deposition.•5–7 nm thin Sb2Te3 films were synthesized for the first time.•Ultrathin films can be grown on mica, quartz, and graphene substrates.•Quality of ultrathin films formed by physical vapor deposition is comparable with the molecular beam epitaxy–deposited.•The ultrathin films–based thermoelectric module is demonstrated.