Preparation and characterization of indium oxide and indium tin oxide films by activated reactive evaporation

Transparent and conducting oxide films find many applications because of their excellent properties such as high optical transparency, low surface resistance, high infrared reflectance, etc. Realization of these properties depend upon the choice of the deposition technique and the control of deposition parameters. In this paper, we report the preparation of highly transparent and conducting films of indium oxide (In2O3) and indium tin oxide (ITO) by activated reactive evaporation on glass substrates. These films were deposited by evaporating pure indium and 90% In + 10% Sn alloy using an electron gun in the presence of oxygen ions at ambient temperature. Films of different thickness have been prepared and their optical, electrical and structural properties are studied. In2O3 films showed higher transparency (90%) compared to ITO films (85%) but the electrical resistivity was observed to be little higher (2.5 x 10(-3) Omega cm) compared to ITO films (6 x 10(-4) Omega cm). Hall measurements on aged ITO films gave the charge density of 3 x 10(20) per cm(3) and mobility 35.6 cm(2)/V-s. The refractive index and extinction coefficient were found to be around 2.0 and 0.005 for ITO films and 2.10 and 0.001 for In2O3 films at 550 nm respectively. ITO and In2O3 films were amorphous in nature for lesser thickness, but for thicker films, the partial crystallinity was observed.