Energy transfer mechanism between terbium and europium ions in zinc oxide and zinc silicates thin films

The aim of this study is to enhance europium ions emission by energy transfer mechanism from terbium to europium ions in codoped ZnO thin films. The samples were annealed with classical and rapid thermal anneal treatments for different temperatures (973 K, 1173 K and 1373 K). Codoped ZnO thin films were characterized for their chemical, structural and photoluminescence properties. Two different terbium concentrations have been studied with roughly constant europium content. Terbium and europium codoping allows an energy transfer from trivalent terbium to europium ions leading to the europium emission hardly observed for ZnO thin films doped by europium only. With thermal annealing above 1173 K, diffusion processes occurred with silicon substrate to form zinc silicate and rare earth oxide with a concomitant photoluminescence signal from trivalent europium ions at 615 nm (⁵D₀ → ⁷F₂ transition). - Highlights: • Formation of silicate phases is observed above annealing temperature of 1173 K. • A classical thermal annealing at 1173 K leads to the highest emission of europium. • Energy transfer mechanism from terbium to europium rare earths is evidenced