K. M. F. Shahil, M. Z. Hossain, V. Goyal, A. A. Balandin
Bismuth telluride - Bi(2)Te(3)- and related compounds have recently attracted
strong interest owing to the discovery of the topological insulator properties
in many members of this family of materials. The few-quintuple films of these
materials are particularly interesting from the physics point of view. We
report results of the micro-Raman spectroscopy study of the "graphene-like"
exfoliated few-quintuple layers of Bi(2)Te(3), Bi(2)Se(3) and Sb(2)Te(3). It is
found that crystal symmetry breaking in few-quintuple films results in
appearance of A1u-symmetry Raman peaks, which are not active in the bulk
crystals. The scattering spectra measured under the 633-nm wavelength
excitation reveals a number of resonant features, which could be used for
analysis of the electronic and phonon processes in these materials. In order to
elucidate the influence of substrates on the few-quintuple-thick topological
insulators we examined the Raman spectra of these films placed on mica,
sapphire and hafnium-oxide substrates. The obtained results help to understand
the physical mechanisms of Raman scattering in the few-quintuple-thick films
and can be used for nanometrology of topological insulator films on various
substrates.
View original:
http://arxiv.org/abs/1201.5678
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