ZNS-TM GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION WITH CL CODOPING

ZnS:Tm and ZnS:Tm,Cl thin films were grown by metalorganic chemical va por deposition (MOCVD), using diethylzinc, H2S, Tm(thd)(3) (thd=2,2,6, 6-tetramethyl-3,5-heptanedione), and HCl. The ZnS:Tm did not contain o xygen which might be introduced through the thd-radical. It thus has o nly codopant-free Tm3+ luminescent centers probably associated with na tive defects. The electroluminescence (EL) spectrum of the ZnS:Tm,Cl s howed three satellite emission lines in addition to the original emiss ion of the ZnS:Tm, indicating the existence of Tm-Cl complex centers. In contrast, the photoluminescence (PL) spectrum of the ZnS:Tm,Cl unde r host excitation showed no discernible satellite emission lines. Henc e, though the Tm ions in the Tm-Cl complex centers are expected to be charge compensated by Cl or a certain Cl-induced defect, they are rath er inactive in the PL excitation while active in the EL excitation. Th e same properties were observed for the MOCVD-grown ZnS:Sm and ZnS:Sm, Cl [A. Kato, M. Katayama, A. Mizutani, N. Ito, and T. Hattori, J. Appl . Phys. 77, 4616 (1995)], and therefore they probably occur for other rare-earth luminescent centers with Cl codopant. (C) 1997 American Ins titute of Physics.