Optical Characteristics of Tin Oxide Thin Films Doped with Indium and Aluminum Using the Sol-Gel Spin Coating Technique

Abstract

The aims of this research are to understand the optical characteristics of SnO2 doped with Indium and Aluminum (SnO2:In+Al) using the sol-gel spin coating technique. Optical characteristics of SnO2:In+Al thin films were measured by UV-Vis Spectrophotometer. The optical characterization results showed that the SnO2:In+Al thin films had an increase in transmittance from (68.6 – 78.3)% at a wavelength of 300 – 470 nm and an increase in absorbance at a wavelength of 295 nm from 4.34 – 5.00 with the increase in the percentage of doping. This shows the thin layer absorbs the maximum waves at a wavelength of 295 nm. The increase in the doping percentage causes the energy gap of SnO2 thin films is decreasing. The direct energy gap decrease from 3.58 to 3.54 eV and the indirect energy gap decrease from 3.90 to 3.87 eV. The energy of optical activation of the SnO2 thin films decreases from 0.97 to 0.86 eV when increasing the doping percentage. This research has indicated that SnO2:In+Al thin films has a low energy gap and high transmittance so that it belongs to be high-quality thin films.