Carrier Injection Observed by Interface-Enhanced Raman Scattering from Topological Insulators on Gold Substrates.

The electron-phonon interaction at the interface between topological insulator (TI), namely, BiSe and BiTe two-dimensional (2D) nanoflakes, to a gold substrate as a function of TI flake thickness is studied by means of Raman scattering. We reveal the presence of interface-enhanced Raman scattering and a strong phonon renormalization induced by carriers injected from the gold substrate to the topological surface in contact. We derive the change of the electron-phonon coupling showing a nearly linear behavior as a function of layer thickness.