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In this study, thin films of transparent semiconductor tin oxide doped with antimony impurities on the glass substrates with different concentrations of antimony that have been prepared using spray pyrolysis method. The effects of different concentration of antimony on the structural, optical, and electrical properties of the thin films were investigated. Prepared layers were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and optical absorption (UV-vis). XRD analysis showed that samples have polycrystalline with orientations (110), (101), (200), (211) and (301) that was related to tin oxide phase. With increasing concentrations of antimony overall average size of nano-crystalline grains increased and the average grain size increased-decreased. Optical studies of samples showed that, increasing of antimony concentration caused reduction of transmission in the range of visible light from 72% to 15% and the optical band gap from 3.72 to 2.98 eV. Increasing of antimony concentration led to increasing-decreasing behavior of electrical resistance. Thermoelectric studies of samples revealed n-type conductivity in them.

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In this research, semiconductor nanoparticles of Aluminum doped zinc oxide (AZO) were synthesized using zinc nitride as a precursor and ethylene-glicol as complexing agent  with Aluminum molar ratio of 0, 2, 4, 6, 8 and 10% by solvo-thermal method.  Crystal structure and surface morphology of the samples were studied by X-ray diffraction analysis (XRD), Field Effect Scanning Electron Microscopy (FESEM) and Tunneling Electron Microscopy (TEM). XRD Results describes the Hexagonal wurtzite structure of zinc oxide with preferred peaks corresponding to (100), (001), (101), (102), (110) and (103) planes. Also by increasing of Aluminum concentration, the preferred peaks shift to higher angles, hence lattice constants have a decreasing trend. While, nano-crystallite sizes have an increasing trend and the sizes were found between 17.5 to 25.2 nm. FESEM and TEM images show that increase of Aluminum concentration causes increase of the nanoparticles size. The optical band gap of the samples was found between 2.03 to 2.66 eV. By increasing Aluminum content from 0 to 4%, band gap decreases and then increases for higher concentrations from 4 to 10%. Investigation of the Acetone gas sensor properties for the sample of 4% impurity shows that maximum response time is for 2300 ppm density which is 60 s and the minimum is 42 s for 3600 ppm.

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In this work, the effect of doping Graphene Quantum Dots (GQDs) on their emission spectra has been studied. First, graphene has been deposited on SiC substrate by using sublimation method. Second, doped-GQDs have been distributed on the surface of graphene via drop casting. The structure of the samples have been studied and characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and Micro-RAMAN spectrometer. Emitted spectra of the doped samples have been studied, and the results show the highest intensity is for K doped samples. The XRD pattern of epitaxial graphene on SiC, represents the structures of graphene and SiC. AFM image shows homogenous surface of epitaxial graphene grown on SiC. Reflectance mapping images obtained from Micro-RAMAN spectrometer confirms the existence of mono- and bi-layers of graphene. The SEM and AFM results show homogenous dispersion of GQDs on the substrate. Results of the emitted spectra of the samples show that by increasing doping of GQDs with B from 0.75% to 1.5% and with K from 2% to 4%, the intensities of emission spectra from GQDs have been increased. Moreover, by increasing doping with N and Cl from 2% to 4%, these emission spectra from GQDs have been decreased. Also, the peaks intensity of K doped GQDs (K-GQDs) are higher than those of B, and for N-GQDs are more than those of Cl. In general, the highest and the lowest peak is for K and Cl, respectively.

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In this research, the diodes were made using a thin films of molybdenum oxide on the doped P-type silicon substrate with the aim of studying the effect of the substrate temperature on the characteristics of the diode. For this purpose, thin films of molybdenum oxide were deposited on the substrate at substrate temperatures of 350, 400, 450 and 500 ˚C by spray pyrolysis. The structural and optical properties of the thin films were characterized. They show a fairly crystalline nature with a straight structure and peaks corresponding to (020), (040) and (060) planes, with the preferred peak being (040) in all samples. The shape of the surface of the samples is without cracks and has a rectangular granulation with the size of the grains in the range of 110 to 210 nm. Also, their average surface roughness was measured in the range of 157 to 167 nm. The optical gap of the samples was estimated in the range of 2.84 to 2.95 eV. The voltage-current diagram of the samples showed their diode behavior. The diode made at 400 ˚C substrate temperature has the lowest threshold voltage.