Authors: M. Gross, I. Maksimenko, H. Faber, N. Linse, P.J. Wellmann
Affilation: University Erlangen-Nuremberg, Germany
Pages: 786 - 789
Keywords: indium tin oxide, nanoparticulate layers, transmittance, absorption, conductance, XPS, ESCA
To improve their conductance we applied several treatments on nanoparticulate indium tin oxide (In2O3:Sn, ITO) layers: post bake, infiltration by an ITO precursor solution with subsequent sol-gel transformation into ITO, treatment with etching agents as well as annealing in vacuum. We obtain a maximum conductance of 119 S/cm by combining the precursor infiltration technique with the vacuum annealing. To understand the mechanisms behind the conductance improvement and to fathom the limits we did some investigations: STM measurements suggest that conductance in nanoparticulate ITO films is mainly limited due to the inter-aggregate charge transfer. From infrared absorption measurements we inferred the free charge carrier density and XPS measurements yield information about the change of oxygen vacancy concentration. Therefore we were able to separate two conductance improving mechanisms: The increase of the free charge carrier concentration by an increase of oxygen vacancy density as well as a release of trapped charge carriers from the aggregate surfaces.