Areej Adnan Hateef, Batool Daram Balawa, Arwaa Fadil Saleh and *Marwa Wailed Mahmmo
Thin films of titanium dioxide TiO2 were prepared using thermal chemical spray pyrolysis technique on glass substrate preheated at (210 oC) with spray rate 3sec./1min, for different thickness (100, 200, 300, 400 and 500 nm). The investigation of (XRD) indicates that the (TiO2) films are polycrystalline type of (anatase). The effect of thickness on some of the electrical properties such as electrical direct conductivity (D.C.) and Hall coefficients has been studied. It is found that (TiO2) films have two activation energies within thermal range (20-200)oC, the first (Ea(1)) at low temperatures varies from (0.0259-0.1465)eV, while the second (Ea(2)) varies from (0.60975- 2.1972) eV, these results observed that the increase in thickness caused increase in D.C. conductivity. Hall coefficients results has shown that the conductivity samples of (TiO2) films was (n-type) for the films at thickness (100-200-300) nm, while it was (p-type) at the thickness (400-500) nm. This inverted (transmutation) in type of carriers charge because of impact defect due to crystal growth in material or because thermal oscillation for atoms around them position in lattice, at high temperatures which may be release atom from its location and leave space behind it, this defect is called vacancies defect.
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