Optical spectroscopy of erbium-doped SrTiO3 crystals

• Published in: Journal of luminescence Vol. 154; pp. 437 - 444
• Main Authors: Potůček, Z., Skvortsov, A.P., Poletaev, N.K., Bryknar, Z., Jastrabik, L., Dejneka, A., Trepakov, V.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2014
• Subjects: Er3+ center; Erbium-doped crystal; Free charge carrier absorption; Optical absorption; Photoluminescence; Strontium titanate; Strontium titanate; Erbium-doped crystal; Optical absorption; Photoluminescence; Er3+ center; Free charge carrier absorption
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2014.05.021

Results of a detailed study of optical absorption and photoluminescence of slightly erbium-doped (~50ppm) strontium titanate (SrTiO3) single crystals are presented. This study allowed us to specify the structure of energy levels that determine the main internal optical transitions within the 4f11 electron configuration of Er3+ ions in SrTiO3:Er crystals at temperatures below the transition from cubic to tetragonal phase. The numbers of energy levels of the studied multiplets obtained at 2K correspond exactly to the theoretically expected numbers of crystal field levels for multiplets of only one type of Er3+ centers with non-cubic symmetry. Experimental results indicate that Er3+ ions most probably substitute for Sr2+ ions acting in SrTiO3 as ionized donors. Such location of Er3+ ions is consistent with both n-type conductivity and substantial free charge carrier absorption in the infrared spectral region observed in the studied SrTiO3:Er single crystals at room temperature. •For the first time observed absorption lines of Er3+ in SrTiO3:Er single crystals.•Only one type of Er3+ centers of non-cubic symmetry was found in the crystals.•Structure of 4f electron energy levels at 2 K was determined for the Er3+ center.•Er-doping results in pronounced free charge carrier absorption in the IR region.