Electrical transport properties of polycrystalline SnO2 thin films

We study the electrical transport properties of degenerate tin dioxide thin films with thickness larger than 250 nm. Our samples have a rutile structure and the effective mass of electron is 0.31 m0, which is obtained from the variation in optical bandgap. The temperature dependence of the Hall mobility indicates that the ionized impurity scattering is the dominant elastic scattering mechanism for electrons. In the low temperature range, the clear negative magnetoresistivity is observed, which can be attributed to the three-dimensional weak localization (WL) effect. By applying the three-dimensional WL theory, we extracted the electron dephasing length, which decreased on increasing temperature. Unexpectedly, the temperature dependence of the extracted dephasing length is found to be dominated by the electron-electron scattering in the small-energy-transfer process and the electron-phonon scattering has negligible contribution. This can be attributed to the low electron concentration in our samples.