Transport properties of Sb2Te3 doped Bi2Te3 thin films

The transport properties of Bi2Te3 and its alloys with Sb2Te3 have been investigated in substantial interest in recent years. In part, these studies have yielded information of immediate interest for the application of these materials in thermoelectric devices operating near room temperature. Bi2Te3 and (Bi2Te3)(70) (Sb2Te3)(30) alloy thin films were deposited at room temperature using the thermal evaporation technique. The thicknesses of the films were measured by using Quartz Crystal Monitor. The structures of films were analyzed using X-Ray diffractogram and are found to be Hexagonal polycrystalline in nature. The structural parameters were calculated and are discussed based on the effect of Sb2Te3 over Bi2Te3 system. The four probe dc resistivity (rho) measurements were done on Bi2Te3 and (Bi2Te3)(70) (Sb2Te3)(30) thin films. A decrease in rho is seen for (Bi2Te3)(70) (Sb2Te3)(30) samples compared to the pure Bi2Te3 samples. The possible conduction mechanism in the films is found to be hopping or tunneling of charge carriers. The activation energy for the corresponding films has been calculated and the results were discussed.