Abstract. In this work a nano-colloidal suspension is used to prepare Nb 2 O 5 thin films. The effect of different substrates on structural properties of niobium pentoxide thin film deposited by spin coating technique on silicon and quartz substrates are presented. We observed that the obtained structure is monocline in both substrates. The diffraction peaks in both substrates ensured the successful formation of Nb 2 O 5 thin films with a clear polymorphous structure. However, the structure became more crystalline with additional distinguished peaks on silicon substrate comparing to quartz substrate. The extracted structural parameters from X-Ray diffraction show that the grain size of the thin films on quartz is smaller than silicon with the values of 16.47 nm and 20.98 nm respectively. The stress measurement records the values of 0.19 and 0.00719 for the thin films deposited on silicon and quartz substrates respectively. Effects of film thickness depicted increment in the absorbance and reduction in the band gap. Energy gaps of 2.7, 2.58 and, 2.5 eV are measured as a result of increasing the film thicknesses of 325, 420 and 450 nm respectively.

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Abstract. This work is dedicated to investigation of temperature effects in Lithium Niobate (LiNbO3) nanostructures. The LiNbO3 nanostructures were deposited on glass substrate by spincoating technique. LiNbO3 was set down at 3000 rpm for 30 sec and annealed from 100 to 600 o C. The structures were characterized and analyzed by scanning electron microscopy (SEM) and ultraviolet visible (UV-vis) spectrophotometer. The measured results have showed that by increasing annealing temperatures, the structures start to be more crystallized and be more homogenized until the optimum arrangement was achieved. Once this was accomplished, it's applicable for optical waveguides development. Eventually, it starts to be less crystallization and non-homogeneous. Energy gap was recorded to be at average value of 3.9 eV.

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