Weak Antilocalization in Granular Sb2 Te3 Thin Films Deposited by MOCVD

Topological insulator (TI) properties of granular Sb2Te3 thin films, grown by MOCVD at room temperature on 400 SiO2/Si substrates, are investigated. The negative magneto-conductance (MC), analyzed in terms of the Hikami-Larkin-Nagaoka theory, reveals the presence of a clear weak antilocalization (WAL) effect, thus demonstrating the TI character of our system. The extracted WAL prefactor (?) values are explained in terms of the film conductance, in agreement with the existing models for WAL in transport disordered systems. The dephasing length (l?) dependence on temperature is affected by the grain size of the film and might in turn explain the observed temperature dependence of ? and of the conductance. These results demonstrate the feasibility of technologically-relevant processes to synthesize TIs films, at the same time providing a tool to investigate the effects of the film microstructure on the topological character of their transport properties.