Initial Stage and Growth Process of Ceria, Yttria-Stabilized-Zirconia and Ceria-Zirconia Mixture Thin Films on Si(100) Surfaces

Abstract

Initial stages and growth processes of ceria ( CeO 2 ), yttria-stabilized-zirconia (YSZ) and ceria-zirconia mixture ( Ce·ZrO 2 ) thin films on Si(100) surfaces were studied in conjunction with O 2 pressure. We showed that (110)-oriented films of CeO 2 , YSZ and Ce·ZrO 2 grew obeying the arrangements of Si atoms in (2×1) or (1×2) structures on a Si(100) surface under about 5×10 -7 Torr O 2 gas at about 900° C. On the other hand, under 1×10 -5 Torr O 2 gas, (111)-oriented CeO 2 polycrystal films grew because of formation of Ce 2 O 3 and Si O 2 layers at the interface between CeO 2 and Si(100). Furthermore, the (100)-epitaxial YSZ and Ce·ZrO 2 films grew, reducing the SiO 2 layer on Si(100) under 1×10 -5 Torr O 2 gas. We attempted to explain these processes in terms of standard formation enthalpies of CeO 2 , Ce 2 O 3 , ZrO 2 and SiO 2 .