Microstructural, linear and nonlinear optical study of spray pyrolysed nanostructured La–ZnO thin film: An effect of deposition temperature

Abstract Transparent Zn0.97La0.03O nanostructures were prepared at different temperatures (300 °C–500 °C) on borosilicate glass substrates using the chemical spray method. The present work focused on the dependence of the substrate temperature (Ts) on the different characteristics of the prepared films. In all the deposits, a polycrystalline structure of La3+ doped ZnO (LZO) film with a preferred orientation along the (101) plane was observed, and a larger crystalline size was noticed for films deposited at lower temperatures. The surface morphology changed from spherical to fibrous structure as a function of the temperature of the substrate. The chemical state and elemental compositions were confirmed by XPS analysis. The linear optical band gap and third-order nonlinear absorption coefficient of LZO films were observed to increase with an increase in substrate temperature. A maximum transmittance was observed for the sample prepared at 450 °C with the least optical limiting threshold value of 0.96 kJ/cm2. The presence of various defects in the film was confirmed through photoluminescence emission, and red emission was noticed for samples prepared at 450 °C and 500 °C.