The carrier capture and recombination processes in Ln(3+)-activated scintillators

The ability of activator ions to capture charge carriers and assume a different charge state under ionizing radiation is essential for efficient performance of rare-earth (RE)-doped scintillator materials utilizing the carrier recombination energy. In this paper the sequence of carrier trapping is discussed and interpreted using a simple, single-configuration-coordinate model for two different cases: In one case (LuPO4:Ce, YAlO3:Ce, LuAlO3:Ce) the charge state involved in the scintillation mechanism is Ce4+, while in the other (LuPO4:Yb, YbPO4) it is Yb2+. The possibility of a nonradiative recombination via Ce and Yb ions is also considered and found highly unlikely in accordance with experimental results.