Opposite pressure impact on electron–phonon coupling in Eu 2+ and Ce 3+ doped AlN

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2023-11, Vol.11 (46), p.16264-16270
• Main Authors: Kamiński, Mikołaj, Lazarowska, Agata, Leśniewski, Tadeusz, Liu, Ru-Shi, Mahlik, Sebastian
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/D3TC03271J

This paper analyzes the influence of pressure on electron–lattice interactions in the 5d excited states of Ce 3+ and Eu 2+ in the AlN host based on pressure-dependent photoluminescence and photoluminescence excitation spectra. High-pressure measurements on AlN samples doped with Eu 2+ and Ce 3+ ions reveal that the Stokes shift increases with pressure for Eu 2+ dopants and decreases for Ce 3+ dopants. Within the interstitial sites of AlN occupied by lanthanide dopants, the effect of crystal field strength on the behavior of luminescent ions can be strongly reduced. Therefore, the observed changes in optical properties under pressure can be interpreted as occurring mainly due to electron–lattice interactions. Based on the experimental data, one can conclude that the barycenter energy of Eu 2+ exhibits virtually no pressure-induced shift (within the experimental error), unlike Ce 3+ , which shows a pressure-dependent redshift. Our findings demonstrate the significance of the specific central ion in the lattice relaxation process.