Amorphous-to-crystalline transition of indium oxide films deposited by reactive evaporation

Amorphous indium oxide films deposited by reactive evaporation of indium in oxygen onto unheated glass substrates were transformed into polycrystalline films by annealing. It was found that the oxygen pressure during deposition affected the optical and electrical characteristics of the polycrystalline films as follows. The film deposited at a low oxygen pressure (0.02 Pa) and subsequently crystallized by annealing had high transmittance and resistivity. In contrast, the film deposited at a high oxygen pressure (0.2 Pa) had low transmittance and resistivity after the amorphous-to-crystalline transition which was accompanied by precipitation of metallic indium in the film. The optimum transparent conductive film which had a resistivity of 2.1 × 10-3 Ω cm and a transmittance of 84% or higher was obtained from an amorphous indium oxide film which was deposited at an oxygen pressure of 0.07 Pa and then annealed in nitrogen at 250°C.