Thickness and temperature effects on electrical resistivity of (Bi0.5Sb0.5)2Te3 thin films

Thin films of (Bi0.5Sb0.5)2Te3 of different thickness were deposited on glass substrate by the flash evaporation method in a vacuum of 1 x 10(-5) Torr. X-ray diffraction and transmission electron microscope analysis indicates that these films are poly crystalline even in the as-deposited state and the post-deposition annealing leads to grain growth. Electrical resistivity studies were carried out on these films as a function of temperature (300- 450 K) and film thickness (450-2000 A(ngstrom)). Temperature dependence of electrical resistivity shows that (Bi0.5Sb0.5)2Te3 films are semiconducting. It is found that electrical conduction activation energy decreases with increase of film thickness and this observation is explained based on the Slater model. Thickness dependence of electrical resistivity is analyzed using the effective mean free path model of size effect with perfect diffuse scattering. This analysis leads to the evaluation of the important physical parameters i.e., mean free path and bulk resistivity of hypothetical bulk.