Serdar Aydin

An investigation of the Nb doping effect on structural, morphological, electrical and optical properties of spray deposited F doped SnO2 films

F and Nb + F co-doped SnO2 thin films were deposited on glass substrates by the spray pyrolysis method. The microstructural, morphological, electrical and optical properties of the 10 wt% F doped SnO2 (FTO) thin films were investigated specifically for niobium (Nb) doping in the range of 0–4 at.% with 1 at.% steps. As shown by the x-ray diffraction patterns, the films exhibited a tetragonal cassiterite structure with (200) preferential orientation. It was observed that grain sizes of the films for (200) and (301) peaks depended on the Nb doping concentration and varied in the range of 25.11–32.19 and 100.6–183.7 nm, respectively. The scanning electron microscope (SEM) micrographs showed that the FTO films were made of small pyramidal grains, while doubly doped films were made of small pyramidal grains and big polyhedron grains. From electrical studies, although 1 at.% Nb doped FTO films have the lowest sheet resistance and resistivity values, the highest figure-of-merit and optical band gap values obtained for FTO films were 16.2 × 10−2 Ω−1 and 4.21 eV, respectively. Also, infrared reflectivity values of the films were in the range of 97.39–98.98%. These results strongly suggest that these films are an attractive candidate for various optoelectronic applications and for photothermal conversion of solar energy.

Study of structural and optical properties of zinc oxide rods grown on glasses by chemical spray pyrolysis

We have investigated morphological and optical properties of zinc oxide rods. Highly structured ZnO layers comprising with well-shaped hexagonal rods were prepared by spray pyrolysis deposition of zinc chloride aqueous solutions at ∼550°C. The rods were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, photoluminescence, and ultraviolet and visible absorption spectroscopy measurements. The deposition of the 0.1mol/L solution at ∼550°C resulted in crystals with a diameter of 400-1000nm and length of 500-2000nm. Sharp near-band edge emission peaks, centered at 3844 and 3680A, dominated the PL spectra of ZnO at 300K and 6.2K, respectively. In addition to this, absorption coefficient was determined by absorption measurement. X-ray diffraction, scanning electron microscopy and atomic force microscopy, results suggest that ZnO rods, prepared by spray pyrolysis, have high crystalline quality. This is desirable in nanotechnology applications.