Thickness and temperature dependence of electrical properties of Bi-2(Te0.1Se0.9)(3) thin films

Thin films of different thicknesses have been vacuum deposited onto clean g lass 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 e lectron microscopy, and selected area electron diffraction techniques. Elec trical resistance and thermoelectric power of the films were measured in th e same vacuum of 2 X 10(-5) Torr in the temperature range 300-450 K. The co nduction activation energy of the films was calculated using the electrical resistivity and thermoelectric power data of the films. The thickness depe ndence of the activation energy observed is attributed to the polycrystalli ne nature of the films. Grain growth and reorientation of the grains take p lace during the annealing process. The thickness dependence of electrical r esistivity and thermoelectric power of the films are explained by the effec tive 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 hypot hetical 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 m aterial. (C) 1999 American Institute of Physics. [S0021-8979(99)05214-7].