Thermoelectric Transport by Surface States in Bi2Se3-Based Topological Insulator Thin Films

We develop a tractable theoretical model to investigate the thermoelectric(TE)transport properties of surface states in topological insulator thin 61ms(TITFs)of BiSeat room temperature.The hybridization between top and bottom surface states in the TITF plays a significant role.With the increasing hybridization-induced surface gap,the electrical conductivity and electron thermal conductivity decrease while the Seebeck coefficient increases.This is due to the metal-semiconductor transition induced by the surface-state hybridization.Based on these TE transport coefficients,the TE figure-of-merit ZT is evaluated.It is shown that ZT can be greatly improved by the surface-state hybridization.Our theoretical results are pertinent to the exploration of the TE transport properties of surface states in TITFs and to the potential application of BiSe-based TITFs as high-performance TE materials and devices.