Electrical Properties of Al₂O₃ Incorporated CeO₂ Thin Films Deposited by RF Magnetron Sputtering

The Al₂O₃ incorporated CeO₂ thin films (Al₂O₃ molar fraction of 0.0 to 0.6) were prepared by the RF magnetron sputtering with the combinatorial mask system using the two targets of Al₂O₃ and CeO₂ in Ar + 10% O₂. The deposited films were annealed in N₂ and O₂ at 500°C for 30 minutes. The minimum leakage current density of 1.6 x 10^-8 A/cm² measured at the electric field of 1MV/cm was obtained for the N₂ annealed sample with the Al₂O₃ incorporation of 0.2, which value was significantly lower than that of the film without the Al₂O₃ incorporation by two orders of magnitude. The variation of the flat band voltage with the incorporated Al₂O₃ molar fraction suggested the generation of the fixed positive charge, which was probably arisen from the lower Ce oxide in the film and/or the lower oxide of Si diffused from the substrate into the film.