Effect of chemical oxide and low temperature long time annealing on the electrical characteristics for rare earth oxides deposited on Si(1 0 0) were investigated. Formation of chemical oxide on Si substrates prior to the Gd2O3 depositions was found to decrease the leakage current significantly compared the films deposited on HF-last Si substrate, when the thickness was 3.5 nm or thicker, while the effect was not observed when the thickness was 2.8 nm. Annealing at 400 degreesC for 90 min also decreased leakage current of Dy2O3 thin films with little increase of capacitance equivalent thickness (CET). (C) 2003 Elsevier Science B.V. All rights reserved.