Binary topological insulator Bi₂X₃ (X=Te, Se) nanoplates have been synthesised via catalyst free chemical vapor deposition method. A silicon nitride protecting layer was deposited after the growth to minimize the damage in Raman spectra measurements of these nanoplates. Temperature dependent non-resonant Raman spectra with the excitation of 514.5 nm show rather small first-order temperature coefficients for all Raman modes in Bi₂Te₃ and Bi₂Se₃ nanoplates compared to the reported value in bulk single crystal. Besides, the A_1g² mode shows an electronic resonant enhancement in Raman spectra with the excitation of 633 nm, which also has a small first-order temperature coefficient as the non-resonant ones. Magnetotransport measurements for grown Bi₂Se₃ nanoplates show pronounced weak...[ Read more ]

Binary topological insulator Bi₂X₃ (X=Te, Se) nanoplates have been synthesised via catalyst free chemical vapor deposition method. A silicon nitride protecting layer was deposited after the growth to minimize the damage in Raman spectra measurements of these nanoplates. Temperature dependent non-resonant Raman spectra with the excitation of 514.5 nm show rather small first-order temperature coefficients for all Raman modes in Bi₂Te₃ and Bi₂Se₃ nanoplates compared to the reported value in bulk single crystal. Besides, the A_1g² mode shows an electronic resonant enhancement in Raman spectra with the excitation of 633 nm, which also has a small first-order temperature coefficient as the non-resonant ones. Magnetotransport measurements for grown Bi₂Se₃ nanoplates show pronounced weak anti-localization effect in the low B-field region, linear magnetoresistance in the perpendicular high B-field and a weak negative magnetoresistance in the in-plane direction. These magnetotransport features are considered to originate from the topological surface states.

Ternary compound Bi₂Te_1.7Se_1.3, Bi₂TeSe₂ and Bi_2.1Te_1.4Se_1.5 nanoplates have been deposited on SiO₂/Si substrates via catalyst free chemical vapor deposition method. The evolution of Raman spectra for Bi₂(Te_1-xSe_x)₃ has been studied, which shows blue shift in A_1g¹, E_g² and A_1g² mode when increase the atomic ratio of Se. A new Raman mode (V) appears in the ternary compound compared to the binary compound, we attempt to attribute this new mode to the Te1-Se2 anti-sites in Bi₂(Te_1-xSe_x)₃.