Two excitation pathways of Pr3+ ion emission in HfO2:Si:Pr films depending on crystalline phase transformations in annealing
Garcia Andrade, Maria Alejandra
Casas Espinola, Jose Luis
Vel´azquez Lozada, E.
The impact of annealing on the emission and transformation of the crystalline phases in Si rich HfO2:Pr films was investigated by analyzing the morphology, chemical composition, structure, and photoluminescence (PL) characteristics. Films were prepared by RF magnetron sputtering and monitored as-prepared and after annealing at 1000 ◦C for 5–60 min. Emission through host HfO2 defects has only been detected in spectra of as-prepared Si rich HfO2:Pr films. Heat treatment for 30 min stimulates a phase transformation together with the appearance of a tetragonal HfO2 phase and Si quantum dot (QDs). This last process is accompanied by appearance of bright emission of rare earth (RE) ions Pr3+ related to the transitions in the 4f energy levels. Additional annealing for 60 min stimulates the complete oxidation of the Si QDs with the formation of the SiO2 phase along with partial destruction of a tetragonal HfO2 phase. This last process is accompanied by the significant increase of the intensity of Pr3+ ion emission. Two forms of luminescence excitation in 4f energy levels of Pr3+ ions are discussed, related to energy transfer to Pr3+ ions, first from Si QDs and then from host defects in HfO2. These changes in the excitation pathways of Pr3+ ion emissions are stimulated by the transformations of the crystalline phases in the thermal treatment together with the generation of host HfO2 defects. Hafnia-based materials doped with RE elements are interesting for telecommunication technology and applications in waveguides and optoelectronic devices.
Si rich HfO2:Pr films, Rare earth (RE) ion Pr3+, bright emission, two excitation pathways, article
Two excitation pathways of Pr3+ ion emission in HfO2:Si:Pr films depending on crystalline phase transformations in annealing / M. A. Garcia Andrade, T. Torchynska, J. L. Casas Espinola, E. Velázquez Lozada, G. Polupan, L. Khomenkova, F. Gourbilleau // Journal of Luminescence. - 2023. - Vol. 258. - Article number 119789. - https://doi.org/10.1016/j.jlumin.2023.119789