Micro-Raman Spectroscopy of Mechanically Exfoliated Few-Quintuple Layers of Bi(2)Te(3), Bi(2)Se(3) and Sb(2)Te(3) Materials

TL;DR

This study uses micro-Raman spectroscopy to analyze the vibrational and electronic properties of exfoliated few-quintuple layers of Bi2Te3, Bi2Se3, and Sb2Te3, revealing symmetry breaking and substrate effects relevant for topological insulator applications.

Contribution

It provides new insights into the Raman-active modes and substrate influences in few-quintuple-layer topological insulators, advancing understanding of their physical properties.

Findings

Appearance of A1u-symmetry Raman peaks due to symmetry breaking

Resonant features in Raman spectra related to electronic and phonon processes

Substrate-dependent variations in Raman spectra

Abstract

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.