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Bi2Te3-Sb2Te3 superlattices grown by nanoalloying

: König, J.; Winkler, M.; Buller, S.; Bensch, W.; Schürmann, U.; Kienle, L.; Böttner, H.


Journal of Electronic Materials 40 (2011), No.5, pp.1266-1270
ISSN: 0361-5235
ISSN: 1543-186X
Journal Article
Fraunhofer IPM ()
thermoelectrics; Bi2Te3-Sb2Te3 superlattices; nanoalloying

In this work, Bi2Te3-Sb2Te3 superlattices were prepared by the nanoalloying approach. Very thin layers of Bi, Sb, and Te were deposited on cold substrates, rebuilding the crystal structure of V2VI3 compounds. Nanoalloyed super- lattices consisting of alternating Bi2Te3 and Sb2Te3 layers were grown with a thickness of 9 nm for the individual layers. The as-grown layers were annealed under different conditions to optimize the thermoelectric parameters. The obtained layers were investigated in their as-grown and annealed states using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray (EDX) spectroscopy, transmission electron microscopy (TEM), and electrical measurements. A lower limit of the elemental layer thickness was found to have c-orientation. Pure nano alloyed Sb2Te3 layers were p-type as expected; however, it was impossible to synthesize p-type Bi2Te3 layers. Hence the Bi2Te3-Sb2Te3 superlattices consisting of alternating n- and p-type layers showed poor thermoelectric properties.