Donor compensation and carrier-transport mechanisms in tin-doped In2O3 films studied by means of conversion electron 119Sn Mossbauer spectroscopy and Hall effect measurements

Donor compensation and carrier-transport mechanisms in tin-doped indium oxide (ITO) thin films were investigated, from the viewpoint of chemical state of tin atoms, by conversion electron Mossbauer (CEM) spectroscopy and Hall effect measurement. Carrier density (n(e)) and Hall mobility (mu(H)), changed with the post-deposition anneals. The carrier density decreased with air-anneal and increased with reducing atmosphere. Analyses of the CEM spectra indicated that the decrease in n(e) with air-anneal was attributed to the compensation of tin donors by excess interstitial oxygen (tin-oxygen complex). Also, we could explain the increase in n(e) with reducing atmosphere in terms of the dissociation of the tin-oxygen complex. From the analyses of mu(H), we arrived at the possibility that the tin-oxygen complex behaved as the screened dipole scattering center.