Sharif Digital Repository

A systematic comparison of single and binary metal oxides TiO2, TiO2-Ga2O3 and TiO2-Er2O3 thin film gas sensors with nanocrystalline and mesoporous microstructure, prepared by a new particulate sol-gel route, was conducted. The gas sensitivity was increased by introduction of Ga2O3 and Er2O3 into TiO2 film via two mechanisms, firstly through the inhibition of anatase-to-rutile transformation, since the anatase phase accommodates larger amounts of adsorbed oxygen, and secondly through the retardation of grain growth, since the higher surface area provides more active sites for gas molecule adsorption. The binary metal oxide gas sensors exhibited a remarkable response towards low... 

In this investigation, the effect of annealing temperature and concentration of gold nanoparticles on the photoelectrochemical properties of sol-gel deposited Au : TiO2 nanocomposite thin films is studied. Various gold concentrations have been added to the TiO2 thin films and their properties are compared. All the deposited samples are annealed at different temperatures. The optical density spectra of the films show the formation of gold nanoparticles in the films. The optical bandgap energy of the Au : TiO2 films decreases with increasing Au concentration. The crystalline structure of the nanocomposite films is studied by x-ray diffractometry indicating the formation of gold nanocrystals in... 

Tin sulfide (SnS2) has recently attracted considerable attention due to its layered structure that may form two dimensional morphologies. It is an n-type semiconductor with band gap and electron affinity similar to CdS and In2S3; therefore can be regarded as an alternative for these materials in thin film solar cells. Here, we synthesis of SnS2 nanoparticles with different morphology in different ratio of water-ethanol mixed solution by solvothermal method, and observe that more ethanol leads to large sheet like morphologies, while water based synthesis results in very small nanosheets. A challenge in wet deposition of device-quality thin films of SnS2 is the requirement for highly dispersed... 

In this study, the effects of TiO2 addition on the physical and photoelectrochemical properties of ZnO thin films have been investigated. The (TiO2)x-(ZnO)1-x nanocomposite thin films were dip-coated on both glass and indium tin oxide (ITO)-coated conducting glass substrates with various values of x, specifically 0, 0.05, 0.1, 0.25 and 0.5. Optical properties of the samples were studied by UV-vis spectrophotometry in the range of 300-1100 nm. The optical spectra of the nanocomposite thin films showed high transparency in the visible region. The optical bandgap energy of the (TiO2)x-(ZnO)1-x films increased slightly with increasing values of x. The crystalline structure of the nanocomposite...