Structural and electrical properties of cerium dioxide films grown by RF magnetron sputtering

A systematic study was performed on the structural and electrical properties of cerium dioxide thin films grown on Si substrate with various deposition temperatures by RF magnetron sputtering. The films grown at 200 degrees C are partly amorphous whereas those grown above 250 degrees C are polycrystalline. An amorphous layer of SiO2 forms at the interface between the cerium dioxide film and the Si substrate. Cerium dioxide film grown at higher temperatures up to 500 degrees C sustains more leakage current on the basis of current-voltage measurements. The electrical conduction of the films is well fitted by a power-law relation, which is explained as space-charge-limited current conduction with exponential distributed traps in the band gap. The variations of dielectric constant, flatband voltage, fixed oxide charge and interface-trapped charge with deposition temperature were studied by making capacitance-voltage measurements on an Al/CeO2/Si structure. The variations of electrical properties with temperature are strongly correlated with the formation of an amorphous SiO2 layer.