Electrical conduction studies on Bi-2(Te0.8Se0.2)(3) chalcogenide thin films

Thin films of Bi-2(Te0.8Se0.2)(3) semiconductor were prepared on clean glas s plates in a vacuum of 2 x 10(-5) ton. The bulk material (charge) was prep ared by melting the appropriate quantities of the required elements in a qu artz ampoule in a vacuum of 2 x 10(-5) ton. 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 activa tion 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 mod el. The mean free path of the electrons in this material was evaluated usin g this model. It is found that the mean free path decreases as the temperat ure increases due to the increased intensity of thermal vibrations of the l attice. (C) 1999 Elsevier Science Ltd. All rights reserved.