Atsushi Mizutani

ZnS:Tm 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...

SATELLITE PEAK GENERATION IN THE ELECTROLUMINESCENCE SPECTRUM OF ZNS:SM GROWN BY METALORGANIC CHEMICAL VAPOR DEPOSITION WITH CL CODOPING

ZnS:Sm, ZnS:Sm,Cl, and ZnS:Cl thin films were grown by metalorganic chemical vapor deposition using the thd‐chelate (thd=2,2,6,6‐tetramethyl‐3,5‐heptanedione) of Sm and hydrogen chloride. 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 that the ZnS:Sm has originally. The ZnS:Sm,Cl also showed photoluminescence attributed to the self‐activated centers, but its intensity was less than 10−2 of that of the ZnS:Cl. The effect of the Cl codoping on Sm3+ luminescent properties is discussed on the basis of the Sm‐VZn (zinc vacancy)‐Cl complex formation.

Gallium‐rich CaGaαSβ:Ce as a new blue electroluminescent phosphor

Ga-rich CaGa α S β :Ce thin films, of which the Ga/Ca ratio was 2.5-4, were grown by metalorganic chemical vapor deposition. After post-annealing at 650°C, a new substance, different from the ordinary CaGa 2 S 4 , grew. This was confirmed by XRD and by a spectral shift of the Ce 3+ emission. This phosphor was found not only to emit a deeper blue, (x, y) = (0.15, 0.16), than CaGa 2 S 4 :Ce, (x, y) = (0.15, 0.19), but also to be electroluminescent. Its luminance was 2 cd/m 2 at 40 V above threshold at a frame frequency of 120 Hz.