Electronic and Vibrational Excitations on the Surface of the Three-Dimensional Topological Insulator Bi$_2$Te$_{3-x}$Se$_{x}$ (x = 0, 2, 3)

Abstract

We study surface states in the three-dimensional topological insulators Bi$_2$Te$_{3-x}$Se$_{x}$ (x = 0, 2, 3) by polarization resolved resonant Raman spectroscopy. By tracking the spectral intensity of the surface phonon modes with respect to the incident photon energy, we show that the surface phonons are qualitatively similar to their bulk counterparts. Using the resonant Raman excitation profile, we estimated the binding energy of the surface conduction bands relative to bulk conduction bands. In addition, by analyzing the Fano interaction between the electronic continuum and the surface phonons as a function of incident photon energy, we determined the spectral properties of the electronic continuum excitations between surface and bulk states in Bi$_2$Se$_3$