Synthesis and characterization of amorphous aluminum oxide thin films prepared by spray pyrolysis: Effects of substrate temperature

Amorphous and non-crystalline aluminum oxide thin films have been deposited on glass substrate by spray pyrolysis method. The structural, morphological and optical properties were investigated using X-Ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV-visible spectrophotometry. For two specific molarities (0.15 M and 0.25 M), substrate temperature was varied between 250 °C, 350 °C, 500 °C, and 550 °C. The XRD results exhibited dominant amorphous nature for all samples as expected, whereas SEM and AFM showed the presence of substrate temperature effects on alumina thin film properties. Enhancement of optical transmittance with temperature increase was observed. Using the transmittance data other optical quantities namely absorption coefficient, optical band gap, refractive index and extinction coefficient, dielectric constants, volume and surface energy loss functions and optical conductivity were determined. It was also observed that the volume energy loss (VELF) increases more than the surface energy loss (SELF).