High-temperature hall measurements on cerium dioxide thin films

Simultaneous Hall and conductivity measurements have been performed on sputtered polycrystalline thin films and on bulk ceramic specimens of nearly stoichiometric CeO2 in the temperature range between 900° and 1040°C. The measurements have been performed in air using low-frequency alternating current. In the case of the bulk ceramic specimens, an upper limit for the carrier mobility of &le0.2 cm2/(V&middots) has been obtained, which is in accordance with data from the literature for bulk samples. The conductivity of the thin films (1/(Ω&middotm) at 1000°C) is in accordance with data from the literature for bulk ceramics. The carrier density derived from the Hall measurements (3 × 1016/cm3 at 1000°C) increases with increasing temperature, whereas the Hall mobility (4 cm2/(V&middots) at 1000°C) decreases with increasing temperature. These values differ from literature data for bulk ceramic specimens. The difference may be due to the small grain diameters (approx.200 nm) in the 1-μm-thick thin films.