Interaction of oxygen with (Er+Si): Formation of erbium pyrosilicate Er2Si2O7

Silicon oxide (SiOx) and erbium oxide (ErOx) layers in the form of SiOx/ErOx/SiOx/Si structures were sequentially deposited onto silicon substrates by reactive RF-sputtering without breaking the vacuum. The structures were subsequently heat treated at 800 degrees C under an argon pressure of 10(-3) mbar. XPS measurements revealed that the layers thus obtained are homogeneous. The relative intensities of the Si2p, Er4d and O 1s core level peaks suggest a Er:Si:O composition ratio equal to 2:2:7, Furthermore, the chemical shifts observed for the Si2p and Er4d peaks showed the formation of a compound in which silicon (Si) and erbium (Er) are, respectively, in tetrahedral and octahedral oxygen environments. XRD measurements showed the formation of erbium pyrosilicate (Er2Si2O7) which is consistent with the XPS results.