Raman spectroscopy of Bi2Se3-x Tex (x=0-3) topological insulator crystals

摘要

We report crystal growth and Raman spectroscopy characterization of pure and mixed bulk topological insulators Bi2Se3-xTex (x = 0-3). The series comprises of both binary (Bi2Se3, Bi2Te3) and ternary tetradymite (Bi2Se1Te2, Bi2Se2Te1, Bi2Se1.5Te1.5) topological insulators. We analyzed in detail the Raman peaks of vibrational modes viz. out of plane A11g, A12g and in-plane Eg2 for both binary and ternary tetradymite topological insulators. Both out of plane A11g and A12g exhibit obvious atomic size dependent peak shift and the effect is much lesser for the former than the later. The situation is rather interesting for in-plane Eg2, which not only show the shift but rather a broader hump like structure. The de-convolution of the same show two clear peaks, which are understood in terms of the presence of separate in plane Bi-Se(I) and Bi-Te(I) modes in mixed tetradymite (Bi2Se2Te1 and Bi2Se1.5Te1.5) topological insulators. Summarily, various Raman modes of well-characterized pure and mixed topological insulator single crystals are reported and discussed in this article.