Electrical conduction studies on Bi 2(Te 0.8Se 0.2) 3 chalcogenide thin films

Abstract

Thin films of Bi 2(Te 0.8Se 0.2) 3 semiconductor were prepared on clean glass plates in a vacuum of 2×10 −5 torr. The bulk material (charge) was prepared by melting the appropriate quantities of the required elements in a quartz ampoule in a vacuum of 2×10 −5 torr. Structural characterization of bulk and thin films was carried out using XRD analysis. Also, transmission electron microscopy and selected area electron diffraction techniques were employed for structural characterization of thin films. Variation of activation energy of the films with film thickness is attributed to the variation of grain size with film thickness. The thickness dependence of resistivity of the films is explained on the basis of the effective mean free path model. The mean free path of the electrons in this material was evaluated using this model. It is found that the mean free path decreases as the temperature increases due to the increased intensity of thermal vibrations of the lattice.