A time-resolved reflectivity study of the amorphous-to-crystalline transformation kinetics in dc-magnetron sputtered indium tin oxide

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Abstract
Amorphous tin-doped indium oxide (ITO) was deposited to a thickness of 110 nm on 〈100〉-oriented Si substrates at ∼40–60 °C by dc-magnetron sputtering under a total Ar pressure of 2 Pa. The kinetics of crystallization of the a-ITO films in flowing N2 were investigated by in situ time-resolved reflectivity. The microstructure of the films in the as-deposited, partially recrystallized and fully regrown conditions was established using a combination of plan view and cross-section transmission electron microscopy and atomic force microscopy. The experimental reflectivity vs time curves were analyzed using classical nucleation and growth kinetic analysis. Various transformation models are proposed and are combined with Fresnel reflectivity calculations for direct comparison to the experimentally obtained data. The activation energy for the crystallization in flowing N2 of these amorphous ITO films in N2 gas was found to be 0.67±0.18 eV.