Thickness and temperature dependence of electrical properties of Bi2(Te0.1Se0.9)3 thin films

Thin films of different thicknesses have been vacuum deposited onto clean glass plates held at room temperature using the flash evaporation technique in a vacuum of 2 X 10(-5) Torr. The structural characterization of the bulk and the thin films was carried out using x-ray diffraction, transmission electron microscopy, and selected area electron diffraction techniques. Electrical resistance and thermoelectric power of the films were measured in the same vacuum of 2 X 10(-5) Torr in the temperature range 300-450 K. The conduction activation energy of the films was calculated using the electrical resistivity and thermoelectric power data of the films. The thickness dependence of the activation energy observed is attributed to the polycrystalline nature of the films. Grain growth and reorientation of the grains take place during the annealing process. The thickness dependence of electrical resistivity and thermoelectric power of the films are explained by the effective mean free path model [C. R. Tellier, Thin Solid Films 51, 311 (1978)]. The important physical parameters like mean free path, Fermi energy, power index of the energy dependant expression for the mean free path, the hypothetical bulk resistivity and the thermoelectric power have been calculated by the combined analysis of electrical resistivity and thermoelectric power. The electron-phonon scattering mechanism is found to be dominant in the material. (C) 1999 American Institute of Physics. [S0021-8979(99)05214-7].