Er3+-catalyzed interdiffusion of elements across the interface between Bi2O3 film and SiO2 substrate resulting in host-material-specific photoluminescence spectra of Er3+

Er3+-doped Bi2O3 thin films were sputter-deposited on SiO2 substrates under various process conditions. After post annealing in an O-2 atmosphere, near-infrared photoluminescence (PL) spectra from Er3+ ions in specific product oxides were observed. For sufficiently oxidized Bi2O3:Er films with Er contents less than 1.5 at%, alpha-Bi2O3:Er having a monoclinic structure nucleated with negligible intermixing of the elements across the interface. Its PL spectra exhibited Er3+ luminescence signals consisting of eight Stark splitting peaks. Deposition at temperatures higher than 400 degrees C and/or with high Er content produced a somewhat reduced Bi2O3 network. Post annealing triggered diffusion of Si into the film as well as diffusion of Bi and Er into the SiO2 substrate, creating Bi2O3 -SiO2 -Er2O3 compound oxides. The original film body crystallized into a delta-Bi2O3 structure, which was stabilized by the presence of a large amount of Er. The emission-active product at Er contents of 2 at% was Bi2O3:Er-SiO2 (Bi2SiO5:Er), which exhibited four-line emission spectra and the intensity was lower than that of alpha-Bi2O3:Er. For Er3+ contents higher than 4 at%, interdiffusion of Si and O atoms was enhanced and SiOx:Er domains were created in the Bi2O3:Er film. Intense and broad emission peaks at 1530 and 1560 nm were observed in the PL spectra. The emission-active species in the Bi2O3-SiO2 -Er2O3 compound oxide will be either Er3+ doped in the strongly disordered delta-Bi2O3 lattice involving oxygen deficiencies or Er3+ attached to SiOx domains formed inside the delta-Bi2O3 network. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

Er3+-doped Bi2O3 thin films were deposited under various process conditions and exhibited different luminescence properties. The structure and composition of the films were influenced by deposition temperature and Er content. The presence of SiO2 substrate and post annealing also affected the formation of compound oxides. The emission spectra showed the characteristic peaks of Er3+ luminescence and indicated the active species in the compound oxide.