Effect of picosecond-laser irradiation on the properties of nanostructured aluminium-doped zinc oxide thin films

Abstract. Thin films of nanostructured zinc oxide doped with aluminium of different concentrations are synthesized on glass substrates, using a spin-coated sol– gel method. The effect of picosecond-laser irradiation on these thin films is studied using different optical techniques. Their structural and optical properties are investigated using X-ray diffraction, near-visible and infrared absorption spectra and photoluminescence. Optical bandgap values are calculated using a Tauc’s method. Slight variation in the relative intensity of X-ray diffraction and broadening of the lines are observed as a result of laser irradiation that causes some disorder in crystallinity. The relative intensities of the absorption and emission spectra decrease with increasing percentage of aluminium and laser-exposure time. The value of this decrease depends on the dopant concentration. Moreover, the emission reveals a slight red shift. The size of nanocrystals also changes at different Al doping percentages and exposure times. The reduction of the relative intensities mentioned above is attributed to changing nanocrystal sizes and structure of a surface layer.