RF-magnetron-sputtered heteroepitaxial YSZ and CeO2/YSZ/Si(001) thin films with improved capacitance-voltage characteristics

Heteroepitaxial yttria-stabilized zirconia (YSZ) and CeO2/YSZ thin films were prepared on Si(0 0 1) by radio frequency (RF)-magnetron sputtering using a combination of metal (Zr+Y), YSZ ceramic and CeO2 ceramic targets. Optimal crystallinity and minimal surface roughness were obtained for a 2-nm thick layer of metallic (Zr+Y). For YSZ thin film, a considerably large threshold hysteresis (memory window) of approximately 2.2 V was observed in the capacitance-voltage characteristics. It was clarified that the memory window can be suppressed by decreasing the thickness of YSZ. The memory window of CeO2(90 nm thick)/YSZ(5 nm thick) thin film was reduced to 0.4 V. (C) 2002 Elsevier Science B.V. All rights reserved.