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.