High‐Temperature Hall Measurements on Cerium Dioxide Thin Films

Abstract

Simultaneous Hall and conductivity measurements have been performed on sputtered polycrystalline thin films and on bulk ceramic specimens of nearly stoichiometric CeO, in the temperature range between 900" and 1040°C. The measurements have been performed in air using lowfrequency alternating current. In the case of the bulk ceramic specimens, an upper limit for the carrier mobility of 50.2 cm2/(V.s) has been obtained, which is in accordance with data from the literature for bulk samples. The conductivity of the thin films ( U ( 0 . m ) at 1000°C) is in accordance with data from the literature for bulk ceramics. The carrier density derived from the Hall measurements (3 X l0l6/cm3 at 1000°C) increases with increasing temperature, whereas the Hall mobility (4 cm*/(V.s) 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 (-200 nm) in the 1-pm-thick thin films.

Accurate Sensors Offering Unrestricted Recal113ration And Long Term Stability For Determining High Temperatures On The Basis Of Gas-sensitive Effects Of Different Gases On Metal Oxides

“…From this effect a maximum error of 20 K can be found. Though the transition temperature from the measurement results given in Figure 1 can be determined to 680 ( rf: 25) "C. nm) have no influence on the transition temperature [2].…”

“…influence of grain diameters on the specific electrical conductivity [2]) lead to the conclusion that the grain-boundary model for SrTiO, thin films can also be applied in the case of CeO, thin films.…”

“…The values for Ce0, depend on the diameters of the grains in the annealed sputtered thin film. Typical values for E, lie between 1.6 f 0.15 eV and 2.0 k 0.15 eV [2]. The accuracy of this method of measuring temperature can be significantly improved if a second transition point from a 'reducing' to an 'oxidising' effect can be found.…”