Microstructural, optical and photocatalytic properties of CdS doped Ti0_2 thin films

摘要

CdS doped Ti0_2 thin films (with CdS content=0, 3, 6, 9 and 12 at%) were grown on glass substrates. The X-ray diffraction analysis revealed that the films are polycrystalline of monoclinic Ti0_2 structure. The microstructure parameters of the films such as crystallite size (D_n) and microstrain (e) are calculated. Both the crystallites size and the microstrain are decreased with increasing CdS content. The optical constants have been determined in terms of Murmann's exact equations. The refractive index and extinction coefficient are increased with increasing CdS content. The optical band gap is calculated in the strong absorption region. The possible optical transition in these films is found to be an allowed direct transition. The values of E~(gpt) are found to decrease as the CdS content increased. The films with 3 at% CdS content have better decomposition efficiency than undoped Ti0_2. The films with 6 at% and 9 at% CdS content have decomposition efficiency comparable to that of undoped Ti02, although they have lower band gap. The CdS doped Ti02 could have a better impact on the decomposing of organic wastes.