Optical characterization of europium and cerium in strontium thiogallate thin films and powders

Luminescent properties of EU(2+) Or Ce3+ doped SrGa2S4 powder samples are investigated over the temperature range 30 to 300 K. Up to 300 K the lifetime remains constant (tau(0) = 480 and 24 ns for EU(2+) and Ce3+, respectively) showing that the probability of non-radiative transitions is negligible at room temperature. The decay of thin films prepared by reactive radio-frequency magnetron sputtering deviates strongly from an exponential one as a consequence of energy transfer to defects. Codoping of Ce3+ with Na+ considerably increases the luminescence efficiency.