Effect of annealing parameters on thermal emissivity of sol - gel derived ITO films on glassAuthor(s): ArijitDe
Tin doped indium oxide (ITO) thin film was deposited on sodalime silica glass substrate by sol-gel dipping technique. Three different concentrations, 6, 8 and 10 wt% equivalent mixed In2O3 and SnO2 maintaining In : Sn = 90 : 10 atomic ratio were prepared starting from inorganic salt precursor. Total thermal emissivity of the deposited films in wavelength range 0.25- 18µm were measured by Integrating sphere method. For films derived from 6 wt % sol emissivity decreases from 0.91 to 0.61 after four deposition steps, whereas for 8 and 10 wt % sol the decrease were from 0.91 to 0.59 and from 0.88 to 0.16 respectively after three layer deposition. Instead of increasing physical thickness, emissivity could be lowered by simply optimizing the annealing atmosphere and time. Reducing atmosphere in this regard proved to be fruitful while annealing time of 3.5 h caused a significant decrease of thermal emissivity value.