Mechanism of enhanced photoluminescence of Tb ions in hydrogenated silicon-rich silicon oxide films

Terbium-doped silicon-rich silicon oxide films were deposited and hydrogenated at elevated temperatures. The influence of hydrogenation on defects-mediated non-radiative recombination of excited Tb³⁺ ions was investigated by means of photoluminescence and photoluminescence decay measurements. An increase in photoluminescence intensity and photoluminescence decay time was observed upon hydrogenation for the main ⁵D₄–⁷F₅ transition of Tb³⁺ ions. This observation was ascribed to saturation of non-radiative recombination defect centers with hydrogen. It was found that the number of emitted photons increases upon passivation as a result of two effects: (1) a reduction of the non-radiative recombination rate, and (2) optical activation of new Tb³⁺ emitters. Based on the obtained results and literature data, Förster energy-transfer was suggested as the interaction responsible for the non-radiative coupling between Tb³⁺ ions and defects. - Highlights: • Tb-doped silicon-rich silicon oxide films were deposited and hydrogenated. • The influence of defect passivation on Tb emission properties was investigated. • Enhancement of Tb photoluminescence intensity was observed upon passivation. • Longer Tb³⁺ lifetime in the 5D₄ excited state was observed upon passivation. • Optical activation of new Tb³⁺ emitters was observed after hydrogenation.