Cerium activated ternary strontium thiogallate phosphor thin films have been deposited by multi-source evaporation of elemental strontium, gallium and sulfur as source materials. Cerium chloride (CeCl3) has been used as activator starting material. In order to avoid SrS as well as Ga phase segregations elemental In as well as compounds, such as LiF, NaF, LiCl, and SrCl2, have been investigated as possible growth enhancing agents. Coevaporation of indium resulted in an improved crystallization with the drawback of an increased reabsorption of the cerium emission. The other additives lead to improved crystal quality combined with true-blue cathodoluminescence (CL) performance (C.I.E. color coordinates of up to 0.14/0.12) which proves phosphor layers without any SrS phase segregations. Thin film electroluminescent (TFEL) devices with SrGa2S4:CeCl3 phosphor layers prepared with LiF as additive exhibit highest ever reported L40 luminances of 78 cd/m2 and luminous efficiencies of 0.017 lm/W at a transferred charge of 1 µC/cm2 with 1 kHz / 50 µs bipolar square wave excitation.

Cerium activated ternary strontium thiogallate phosphor thin films have been deposited by multi-source evaporation of elemental strontium, gallium and sulfur as source materials. Cerium chloride (CeCl3) has been used as activator starting material. In order to avoid SrS as well as Ga phase segregations elemental In as well as compounds, such as LiF, NaF, LiCl, and SrCl2, have been investigated as possible growth enhancing agents.Coevaporation of indium resulted in an improved crystallization with the drawback of an increased reabsorption of the cerium emission. The other additives lead to improved crystal quality combined with true-blue cathodoluminescence (CL) performance (C.I.E. color coordinates of up to 0.14/0.12) which proves phosphor layers without any SrS phase segregations. Thin film electroluminescent (TFEL) devices with SrGa2S4:CeCl3 phosphor layers prepared with LiF as additive exhibit highest ever reported L(40) luminances of 78 cd/m(2) and luminous efficiencies of 0.017 1m/W at a transferred charge of 1 mu C/cm(2) with 1 kHz/50 mu s bipolar square wave excitation.

The luminescence properties of lead ions and their sensitizing effect on cerium activators in strontium sulfide thin-film electroluminescence (TFEL) devices have been investigated. Polycrystalline SrS:Pb and SrS:Ce,Pb thin active layers for such TFEL devices have been prepared by multi-source deposition. Emission spectroscopy under application of a high electric field (EL), under e-beam excitation [cathodoluminescence (CL)], and under CL conditions with additional EL drive has been carried out. It has been found that the luminescence of SrS:Pb under EL drive is very weak, while the CL signal is considerably higher. This CL signal has shown strong quenching effects upon application of an additional ac voltage. The Pb2+ emission dropped to some 5% at an applied voltage of 100 V0p, being roughly 40 V below EL threshold. More than half of this drop occurred between 0 and 30 V0p. A remarkably lower quenching effect on the Ce3+ activator luminescence has been observed. Such luminescence quenching is attributed to the field induced ionization of the luminescent ions. From the obtained results it is concluded that the optical energy transfer from Pb2+ sensitizers to Ce2+ activators in SrS TFEL devices is low.

Cerium activated strontium sulphide (SrS:Ce) phosphor layers for thin film electroluminescence (TFEL) devices have been prepared using a multi-source deposition method. CeCl3 has been used as dopant starting material for reference SrS:Ce,Cl samples. Additionally, CeF3 has been employed in several cerium concentration series to study the influence of the halides, The concentrations of cerium and of the halide in all layers have been determined by X-ray photoelectron spectroscopy (XPS). Cathodoluminescence (CL) and electroluminescence (EL) emission spectra of luminance-optimized phosphor films have been measured. Additionally, the effect of the halide containing codopants LiCl and LiF on the emission characteristics has been studied.The maximum EL luminances have been found at cerium concentrations of 0.26-0.28 at%. The cerium to halide ratio has been determined to 1:1 for all doping and codoping experiments. CL spectra of the corresponding active layers yield the C.I.E.1931 colors yellowish green in standard SrS:Ce,Cl and bluish green in SrS:Ce,F phosphors. Moreover, codoping with LiCl resulted in no mentionable spectral change, whereas the emission of SrS:Ce,Cl:LiF shifted to green. The measured blue shifts have been attributed to the Nephelauxetic Effect.

The flux-assisted deposition of the active phosphor layer in the highest efficiency, true blue (CIE coordinates of x = 0.14y = 0.12) electroluminescent (EL) devices based on SrGa2S4:Ce,Cl is described. Luminances of 78 cd/m2 luminous efficiencies of 0.017 lm/W at a transferred charge of 1 μC/cm2 with 1 kHz/50 μs bipolar square wave excitation were achieved. The influence of the coevaporated fluxes LiF and NaF in addition to the elements Sr, Ga, S, and the activator starting material CeCl3, on film growth is examined. The relation between GaSr, SSr, fluxSr rates, and substrate temperature (TSub) on phase homogeneity due to flux, crystal quality, film thickness, and device performance is described.

Polycrystalline thin films of the ternary chalcopyrite semiconductors CuIn3Se5 and CuInSe2, prepared by a coevaporation process, have been investigated with the Temperature Programmed Desorption method (TPD). The desorbing species have been detected with a mass spectrometer for temperatures up to 750°C. Morphological changes have been observed with SEM and compositional data have been recorded before and after the heat treatments. The decomposition process has been found to start at about 500°C with outgasing of Se2 species, followed by the desorption of In2Se starting at 600°C. CuIn3Se5 thin films could be transformed totally to Cu2Se.