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Electroluminescent ZnS:Mn thin films have been codoped with KCl via an ex situ deposition and diffusion process. The brightness, efficiency, and stability of sputter deposited ZnS:Mn alternating current thin film electroluminescent devices have been greatly improved over untreated devices. Potassium chloride doping is shown to have a modest fluxing effect on the grain size of ZnS:Mn films, particularly in the region of the film where nucleation occurs. However, improved electroluminescence is postulated to be strongly influenced by doping control of electric fields and injected charge. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Thin films of ZnS:Tb,F were sputter deposited from a ZnS:TbF3 target in an oxygen-argon ambient. The highest electroluminescent brightness (82 cd/m2 at 60 Hz) was measured from ZnS:Tb,F films with a 3.6 at% oxygen concentration. Oxygen concentrations above or below this concentration resulted in sharp decreases in brightness (56 cd/m2 at 2.2 at% oxygen, and 42 cd/m2 at 8.1 at% oxygen). The brightness improvement by oxygen codoping between 0 and 3.6 at% results from increased conduction charge with increasing oxygen concentrations. The brightness decrease for oxygen >3.6 at% is attributed to decreases of both excitation and radiative efficiencies. Improved electroluminescent brightness from oxygen codoping during sputter deposition of ZnS:Tb,F films was equivalent to the improvement observed in films deposited from a ZnS:TbOF target. [Copyright &y& Elsevier]

Mn-doped ZnGa2O4−xSex thin film phosphors have been grown using pulsed-laser ablation at the various growth conditions. Structural characterization was carried out on a series of ZnGa2O4−xSex:Mn2+ films grown on MgO(1 0 0) substrates using Zn-rich ceramic targets at various substrate temperatures and oxygen pressures. The films grown under different conditions not only have different crystallinity and surface morphology but also different Zn/Ga composition ratio. The luminescent results indicated that MgO (1 0 0) is one of the most promised substrates for the growth of high quality ZnGa2O4−xSex:Mn2+ films and the luminescent brightness is sensitive to the substrate temperature and oxygen pressure. In particular, the incorporation of Se into ZnGa2O4:Mn2+ lattice induced a remarkable increase of photoluminescence (PL). The highest green emission intensity was observed with ZnGa2O3.925Se0.075:Mn2+ films, whose brightness was increased by a factor of 3.1 in comparison with that of ZnGa2O4:Mn2+ films. This phosphor is promising for applications in flat panel displays. [Copyright &y& Elsevier]

The microstructure and electroluminescence (EL) characteristics of ZnS:Mn doped with KCl for alternating current thin film electroluminescent devices deposited by a RF sputter system from ZnS and Mn targets are investigated. Transmission electron microscopy (TEM), X-ray diffractometry, energy dispersive spectrometry (EDS), secondary ion mass spectrometry, EL brightness and luminous efficiency (η) measurements were carried out. The as-deposited films have a 100 nm layer of equiaxed grains at the insulator/phosphor interface and columnar grains in the rest of the film. K is uniformly distributed through the 1 μm ZnS film after 5 min anneals at T⩾600 °C, while Cl requires an anneal at T⩾700 °C before diffusion results in a uniform concentration. Upon annealing at 700 °C for 5 min, the equiaxed grains were consumed by growth of the columnar grains, and growth of the columnar grain diameter is enhanced by the presence of KCl. The mixed cubic and hexagonal atomic stacking observed in as-deposited films became more cubic upon annealing with KCl co-dopants. EDS data from plan-view TEM samples indicate that K did not segregate to the grain boundaries. Considering the large ionic radius of K+ relative to Zn2+ (1.51 vs. 0.74 A˚), and the small temperature dependence of K diffusion into ZnS, it was postulated that K+ diffuses by an interstitial mechanism. In addition, it occupies an interstitial site in the cubic structure where it acts as a donor, similar to substitutional Cl−. ZnS:Mn co-doped with KCl shows significant improvement in EL brightness and luminous efficiency. It was concluded that the improved EL properties result from both improved crystallinity and modification of point defects and space charge in the ZnS:Mn, K, Cl films. [Copyright &y& Elsevier]