Influence of the initial layers on the optical and electrical properties of ITO films

The influence of early stage growth structure of indium tin oxide (ITO) thin films, deposited by reactive thermal evaporation (RTE) on optical and electrical properties, was studied by atomic force microscopy (AFM) measurements. ITO thin films were deposited at T-s = 440 K from an In:Sn alloy in the presence of added oxygen with (series A), and without (series B) a shutter between the substrate and the crucible. In series A, the presence of crystallisation seeds smaller than 20 nm was observed in the initial stages of growth. The mean grain size value and the number of grains per aggregate increased with film thickness reaching, respectively, 50 nm and 8 for t = 100 nm. In series B, the initial stages show the presence of individual features with characteristics dimensions of up to 100 nm scattered on the surface. With increasing thickness ITO thin films of series B appear to grow similarly to series A. In series A, both transmittance and sheet-resistance were improved. (C) 2001 Elsevier Science B.V. All rights reserved.