Figure 5

Micro-Raman spectra of the commercial n-type Bi2Te3 ingot and the exfoliated samples in the low (panel a), mid (panel b) and high-frequency regions (panel c).
Although there are no significant changes in the low-frequency region (panel a), the mid- and high-frequency regions (panels b and c) show the presence of distinct peaks that possibly arise due to defect-induced symmetry breaking. Importantly, the sharp peak at ~ 760 cm−1 (in panel c) is observed to change with exfoliation time as shown in the inset of Fig. S6.