Thermopower and resistivity of the topological insulator Bi2Te3in the amorphous and crystalline phase

We have,in-situ, prepared and measured the temperature dependence of thermopowerS(T) and resistanceR(T) of Bi2Te3topological insulator (TI) thin films in the amorphous and crystalline phase. Samples were prepared by sequential flash-evaporation at liquid4He temperature. TheS(T) in the amorphous phase is negative and much larger compared to other known amorphous materials, while in the crystalline phase it is also negative and behaves linearly with the temperature. The resistivityρ(T)in the amorphous phase shows a semiconducting like behavior that changes to a linear metallic behavior after crystallization.S(T) anρ(T)results in the crystalline phase are in good agreement with results obtained both in bulk and thin films reported in the literature. Linear behavior of theρ(T)forT > 15 K indicates the typical metallic contribution from the surface states as observed in other TI novel materials. The low temperature conductivityT