Effect of annealing on the structural and electrical properties of In2Te3

Amorphous In2Te3 was prepared in both bulk form, by quenching the molten material, and thin-film form, by the thermal evaporation technique. X-ray diffraction analysis showed that the prepared samples in bulk and as-deposited thin-film forms were in the amorphous state. beta- and alpha-phases of In2Te3 were prepared by annealing bulk samples at 615 and 813 K, respectively. Films annealed at 573 K give beta-phase polycrystalline structure. The electrical conductivity for the as-deposited In2Te3 films increases with increasing film thickness. The conduction activation energy, Delta E-sigma, of the as-prepared bulk and thin film samples were found to be 0.516 and 0.521 eV. The corresponding values of room-temperature electrical conductivity, sigma(RT), for these samples are 1.1 x 10(-6) and 7.15 x 10(-7)Omega(-1) m(-1), respectively. The observed change in the value of sigma(RT) may be due to the difference in the structure of bulk and thin-film samples. The increase of Delta E-sigma with annealing temperature for both bulk and thin-fi Im samples is interpreted in terms of the density of states model proposed by Mott and Davis. (C) 1998 Chapman & Hall.