Characterization of composite PVA-Al2O3 thin films prepared by dip coating method

Composite poly (vinyl alcohol)-aluminum oxide (PVA-Al2O3) thin films were successfully prepared on precleaned glass plates by dip coating method. The presence of metal-oxide (M-O) bond in the films was identified by Fourier transform infrared spectroscopy. The X-ray diffraction patterns revealed that both the as-grown and annealed films were predominately amorphous in nature. The scanning electron micrograph images showed that Al2O3 particles were distributed on the film surface and the size of the grains increased upon annealing. The energy dispersive X-ray spectroscopy analysis confirmed the presence of Al and O elements in the prepared films. The optical transmittance was found to be about 80 % for the as-grown film, whereas it was found to be increasing with the increase of annealing temperature and the band gap energy (3.74-3.78 eV) value decreased with the increase of annealing temperature. The frequency and temperature dependence of capacitance, dielectric constant, dielectric loss and AC conduction properties were investigated and the results showed enhanced dielectric properties. The obtained results indicated that the higher transmittance, wide band gap energy with high refractive index and high dielectric constant with low dielectric loss of the prepared composite PVA-Al2O3 thin films could be used as high-k layer in thin film transistors and optoelectronic devices.