Anatase (A), rutile (R) and amorphous phase TiO2 thin films have been prepared by RF magnetron sputtering on unheated glass substrates by controlling the total pressure of sputtering gases (Ar + O2) and the substrate bias. The crystal structures of the films were confirmed by x-ray diffraction and Raman scattering. The analysis of optical absorption data for A- TiO2 film shows an energy bandgap (Eg) of 3.2 eV (indirect extrapolation) and ∼ 3.5 eV (direct extrapolation). On the other hand, R-TiO2 film shows Eg ∼ 2.9 eV (indirect) and 3.2 eV (direct). The latter film also shows the presence of amorphous regions with Eg ∼ 3.0 eV (indirect) and 3.8 eV (direct). The bandgap of both the films, obtained using indirect extrapolation, has a value range consistent with the previous measurements.

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The temperature dependence of Hall mobility, µ , and carrier density, e N , for thin InN films grown by Molecular Beam Epitaxy and Plasma Source Molecular Beam Epitaxy have been investigated. For temperature up to 300 K, a large temperature-independent e N is observed in films grown by the above two techniques. However, for higher temperatures, carrier density (N e ) increases with temperature. The characteristic behavior of the mobility for the films with low carrier density is different from that of the high carrier density film, particularly at low temperatures. The low carrier density film shows a peak ~250 K in mobility as a function of temperature which is contrast to the temperature independent mobility observed for the high density film for T < 300 K. We have investigated theoretically the effect of concentration of donor, acceptor, and threading dislocations on the carrier mobility in these films. Various electron-scattering mechanisms for the mobility in these films have been discussed.