Excitation of Er3+ ions in silicon dioxide films thermally grown on silicon

We investigate photoluminescence (PL) and photoluminescence excitation spectroscopy of ${\mathrm{Er}}^{\mathrm{3+}}$ ions implanted into ${\mathrm{SiO}}_{\mathrm{2}}$ films thermally grown on silicon wafers. We show that at 10 K the ${\mathrm{Er}}^{\mathrm{3+}}$ PL excited with the 514.5 nm line of an Ar laser is limited by the total number of Er ions, whereas at resonant excitation within the 960–1000 nm range the PL efficiency is rather concentration limited. Some samples were codoped with ${\mathrm{Yb}}^{\mathrm{3+}}$ ions to study sensitization of the $\text{4f–4f}$ PL of ${\mathrm{Er}}^{\mathrm{3+}}$ ions. At resonant excitation the presence of Yb leads to an enhancement of the ${\mathrm{Er}}^{\mathrm{3+}}$ PL only at dilute Er concentrations.