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

Abstract

ZnS:Tm and ZnS:Tm,Cl thin films were grown by metalorganic chemical vapor 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 oxygen which might be introduced through the thd-radical. It thus has only codopant-free Tm3+ luminescent centers probably associated with native defects. The electroluminescence (EL) spectrum of the ZnS:Tm,Cl showed three satellite emission lines in addition to the original emission of the ZnS:Tm, indicating the existence of Tm–Cl complex centers. In contrast, the photoluminescence (PL) spectrum of the ZnS:Tm,Cl under host excitation showed no discernible satellite emission lines. Hence, 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 rather inactive in the PL excitation while active in the EL excitation. The 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.

Blue emitting thin-film electroluminescent devices utilizing Tm-doped ZnS nanocrystals

“…Kato et al, reported that the 1 G 4 ! 3 H 5 transitions of Tm 3+ is quenched due to the existence of ion-pair relaxation between Tm 3+ ions in the MOCVD-grown ZnS thin film at high (over 1 mol%) Tm concentrations [10]. Thus, the high Tm concentrations from 1 to 15 mol% of our TFEL devices are responsible for quenching of the 1 G 4 !…”

Superior Destabilization Effects of MnF2 over MnCl2 in the Decomposition of LiBH4

“…In addition to the above cation substitution, anion substitution is also an effective method to improve the decomposition properties of complex hydrides. − Since the ionic radius of fluorine anions (F – , 1.36 Å) is quite close to the ionic radius of hydrogen anions (H – , 1.37 Å), the partial substitution of F – for H – in LiBH 4 is possible. For example, Gosalawit-Utke et al reported that the kinetics of a 2LiF/MgB 2 –H 2 system is significantly improved due to the formation of some hydridofluoride phases (LiBH 4– x F x and LiH 1– y F y ).…”

“…In addition to the above cation substitution, anion substitution is also an effective method to improve the decomposition properties of complex hydrides. 22À26 Since the ionic radius of fluorine anions (F À , 1.36 Å) 27 is quite close to the ionic radius of hydrogen anions (H À , 1.37 Å), 28 the partial substitution of ABSTRACT: A 3LiBH 4 /MnF 2 composite was prepared by mechanically milling a mixture of LiBH 4 and MnF 2 . The decomposition properties of the 3LiBH 4 /MnF 2 composite were investigated and compared with those of the 3LiBH 4 /MnCl 2 composite.…”

Effects of La fluoride and La hydride on the reversible hydrogen sorption behaviors of NaBH4: a comparative study

“…However, lanthanide hydrides as reactants working on the dehydrogenation process of NaBH 4 have not been investigated yet. In addition, though the uorine anion (F À , 1.36 Å) 27 and the hydrogen anion (H À , 1.37 Å) 28 have similar ion radii and the same valence of À1, metal uorides usually show superior performance to the same metal hydrides as additives. For instance, TiF 3 exhibited superior catalytic effects than TiH 2 on the dehydrogenation of MgH 2 (ref.…”