Material properties of heteroepitaxial zirconia films on (100) Si with the controlled yttria Y2O3 contents have been studied. The epitaxial zirconia films were prepared by dc magnetron reactive sputtering with Ar + O-2 gas, where the metallic Zr + Y films were deposited on the weakly oxidized Si substrates prior to the zirconia films deposition. If was found from XRD and RHEED measurements that the 100 nm-thick zirconia films have cubic crystal structures for the yttria content of 1.2-10.9 mol%. For 0.6 mol%, the phase change of the zirconia film was observed during the cooling process from the growth temperature of 800 degrees C by means of RHEED measurement At the growth temperature, the deposited film on Si is a cubic (100) zirconia while at the room temperature if is a bilayer of monoclinic zirconia/cubic (100) zirconia. The hysteresis width of the capacitance-voltage (C-V) characteristics due,to ion drift is reduced by decreasing the plasma radiation to the growing film although the amount of the fixed charge in the films is hardly affected (C) 1998 Elsevier Science Ltd. All rights reserved.