No abstract

Tin oxide thin films doped with iron or copper were deposited on glass and porous alumina substrates, using the co-deposition dip coating sol-gel technique. Alumina substrate was prepared by the anodizing technique. Samples were sintered for 2 h at temperature 600°C. The XRD spectrum of deposited samples shows a polycrystalline structure with a clear characteristic peak of SnO 2 cassiterite phase. From (I-V) characteristics measured at different temperatures for samples prepared on glass substrates, the density of states at the Fermi level was calculated. Thermoelectric effect was measured with a change of temperature for prepared samples under low pressure 1 mbar. Seebeck coefficient, the carrier concentration, the charge carrier mobility and the figure merit were determined for prepared samples under low pressure 1 mbar. Seebeck coefficient was improved when films were deposited on porous Alumina substrates.

The PbTe films were deposited onto glass substrate (microscopic slices) by a chemical bath method (CBD) at room temperature. The deposited films are dense, smooth, and uniform with silver gray metallic luster structure. Using XRD, it found that the structure of PbTe possesses stable face centered cubic (fcc) phase. The grain size of the PbTe bulk increased within the range of 33-57 nm with annealing temperature increasing. AFM micrographs of surface of the prepared film are observed that horizontal distance in the rang (230-395) nm. The band gaps of the PbTe are determined from UV-Vis spectrophotometer and are found to be within the range (0.39-0.95) eV. Energy band gab of PbTe which determined from FT-IR spectrophotometer is (0.36ev). The activation energy varied from 0.35-1.72 eV for films and from 0.11-0.34 eV for bulk with annealing temperature variations from 373-573K. Films and bulk exhibit p-type conduction and resistivity in the range (75×10-4 Ω. cm-146×10-4 Ω .cm). The carriers density and Hall mobility in PbTe bulk were in the rang 5.8 ×10 23 m-3 and 4.004 m 2 /Vs.