Preparation of In₂O₃ thin film by dip-coating method

The In₂O₃ thin films were prepared on glass substrates by sol-gel technique and dip-coating of an aqueous In(OH)₃ gel prepared from InCl₃·4H₂O and PVA, followed by drying at 110℃ and calcinating at 400℃. The relationships between the thickness of In₂O₃ thin films and In₂O₃ content, viscosity of the dipping solution and raising rate were investigated. It is found that there are well logarithmic-linear relationships between film’s thickness and viscosity of the dipping solution, raising rate. The thickness(t)of In₂O₃ thin films and the raising rates(v) of substrates from dipping solutions are correlated with an expression of t≈v^0.62. The results obtained from XRD and IR show that PVA is completely removed after calcination at 400℃. SEM photographs show the morphologies of the thin films are flat and bright, so that it is possible to prepare practical In₂O₃ gas sensor by using this film.