Photoluminescence and positron annihilation spectroscopy investigation of (Ge, Er) codoped Si oxides deposited by magnetron sputtering

We have investigated the nature of violet-blue emission from (Ge, Er) codoped Si oxides (Ge+Er+SiO2) using photoluminescence (PL) and positron annihilation spectroscopy (PAS) measurements. The PL spectra and PAS analysis for a control Ge-doped SiO2 (Ge+SiO2) indicate that Ge-associated neutral oxygen vacancies (Ge-NOV) are likely responsible for the major emission in the violet-blue band. For Ge+Er+SiO2, both Ge-NOV and GeO color centers are believed to be responsible for the emission band. The addition of Er has a significant influence on the emission, which is discussed in terms of Er-concentration-related structural change in the Ge+Er+SiO2.