Electrical and optical properties of thin films consisting of tin-doped indium oxide nanoparticles

Abstract

Electrical transport and optical properties were investigated in porous thin films consisting of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{Sn}$ (indium tin oxide, ITO) nanoparticles with an initial crystallite size of $\ensuremath{\sim}16 \mathrm{nm}$ and a narrow size distribution. Temperature dependent resistivity was measured in the $77 130\mathrm{K}$ and negative at $t<130\mathrm{K}.$ Effects of annealing on the ITO nanoparticles were investigated by analyzing the spectral optical reflectance and transmittance using effective medium theory and accounting for ionized impurity scattering. Annealing was found to increase both charge carrier concentration and mobility. The ITO nanoparticles were found to have a resistivity as low as $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\ensuremath{\Omega}\mathrm{cm},$ which is comparable to the resistivity of dense high quality ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{Sn}$ films. Particulate samples with a luminous transmittance exceeding 90% and a resistivity of $\ensuremath{\sim}{10}^{\ensuremath{-}2}\ensuremath{\Omega}\mathrm{cm}$ were obtained.