Initial growth analysis of Si overlayers on cerium oxide layers

Abstract

${\mathrm{CeO(OH)}}_{\mathrm{2}}$ and ${\mathrm{Ce(OH)}}_{\mathrm{4}}$ capped on cerium oxide were observed in x-ray photoemission spectroscopy. Since the cerium oxide surface is partially covered with hydroxide before Si deposition, the Si layer is expected to have a poor crystal quality at the initial Si growing stage. Cross-sectional transmission electron microscopy analysis verified that there was not ${\mathrm{SiO}}_{\mathrm{2}},$ but amorphous Si and ${\mathrm{Ce}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ between the Si overlayer and ${\mathrm{CeO}}_{\mathrm{2}}.$ The reason why ${\mathrm{SiO}}_{\mathrm{2}}$ is not formed is explained. The transition of the growth mode for the Si overlayer was observed in atomic force microscopy images. It is confirmed that the growth mode of Si on ${\mathrm{CeO}}_{\mathrm{2}}\mathrm{/Si}$ is step flow at the low deposition rate and island growth at the high deposition rate.