Optimization of ITO thin film properties as a function of deposition time using the swanepoel method

This work reports the effect of deposition time on the properties of indium tin oxide ITO thin film deposited by RF magnetron sputtering on glass and Si substrates. The structural investigation shows that the as-deposited ITO thin films on a glass substrate have a polycrystalline structure, where the crystalline size increase with the deposition time. Moreover, the XRD results reveal that the ITO films have a cubic structure preferentially oriented along (222) and (622) planes. AFM results show an increase of the surface roughness from 1.2 nm to 2.2 nm. The optical transmittance spectra show high transmittance of more than 80 % for all samples at the visible and near-infrared ranges. The optical band gap varied between 3.52 eV and 3.59 eV with the increasing deposition time. In addition, the optical analysis gives a normal dispersion for the refractive index that has values varied between 1.5 and 1.65. The Swanepoel method was deployed for calculating thicknesses of ITO thin film. The method demonstrated the thicknesses increase from 141.3 nm to 816.0 nm for 60 min. Further, the calculated thickness agrees with the FESEM cross-section results. The EDX results of the ITO thin film show the concentration of the element increased with the increase of the film thickness. The properties of ITO thin films can be controlled by the amount of deposition time. This is an important parameter in the applications of solar cell work as a transparent conducting layer.