ZnS:Sm grown by metalorganic chemical vapor deposition with Cl codoping

Sm-doped ZnS thin films were grown by metalorganic chemical vapor deposition using diethyl- zinc, H2S, Sm(thd)3 (thd=2,2,6,6-tetramethyl-3,5-heptanedione), Sm(hfa)3 (hfa=1,1,1,5,5,5- hexafluoro-2,4-pentanedione), SmCl3, and HCl. The following films were prepared: an undoped ZnS, a ZnS:Sm grown with Sm(thd)3 and without HCl, a ZnS:Sm,Cl grown with both Sm(thd)3 and HCl, a ZnS:Cl grown only with HCl, and a ZnS:SmCl3 grown with SmCl3. Very little Sm was incorporated when Sm(hfa)3 was used as the dopant source. In the ZnS:Sm, the Sm was not segregated at grain boundaries, at least at concentrations below 0.2 at. %. In the ZnS:Sm and the ZnS:Sm,Cl, the (200), (220), and (311) reflections of the cubic structure that the undoped ZnS and the ZnS:Cl exhibited were not detected, and preference for the (00⋅1) hexagonal orientation became stronger. The electroluminescence spectrum of the ZnS:Sm,Cl showed three satellite peaks appearing in each of the 7 nm ranges around the three dominant peaks seen in the ZnS:Sm. The total electroluminescence intensity of the ZnS:Sm,Cl increased as a result of the appearance of the satellite peaks. While the ZnS:Sm,Cl showed photoluminescence attributed to the self-activated centers, its intensity was less than 10−2 of that of the ZnS:Cl. A model is suggested that Sm-VZn (zinc vacancy)-Cl complex centers are formed by the Cl codoping and give rise to the satellite peaks.