Electrical and optical properties of Er3+-doped indium tin oxide thin films fabricated via a sol-gel technique

We have fabricated the Er-doped indium tin oxide thin films via the conventional sol-gel technique, and confirmed a homogeneous spatial distribution of trivalent Er ions. The Er3+ ions were optically active, thus emitting a strong photoluminescence centred at similar to 1.5 mu m originating from the Er3+ : I-4(13/2) -> I-4(15/2) transition. The emission spectra turned out to be inhomogeneously broadened, and the measured lifetimes showed negligible concentration quenching up to an Er concentration of 5 at%. Er L-3-edge EXAFS spectroscopic analysis indicated that the Er3+ ion replaced the more distorted site out of the two octahedral sites available for In3+. Concentrations of Er and Sn together with other processing parameters such as volume ratio of solvents and heat treatment conditions were varied. The accompanying changes in structural, electrical and optical properties were then discussed.