The basic data of the luminescence of SrS:Ce3+ and Ce3+ or Eu2+-doped SrGa2S4 samples have been determined in powder samples under optical excitation. The study of the cathodoluminescent properties of SrGa2S4:Ce has shown that this material possesses the characteristics required for use as a blue-emitting phosphor in high-current density cathodic screens.
The electroluminescence characteristics of thin films have been investigated. SrS:Ce thin films have been obtained by reactive evaporation using CeCl3 or CeF3 as cerium source. The efficiency of SrS:Ce films prepared by atomic layer epitaxy (ALE) has been improved by using in situ synthesized or triglyme-adducted Sr(thd)2 precursor. The effect of codoping with halide or alkali ions in films deposited by ALE has been examined.
It has been shown that it was possible to grow blue-emitting SrGa2S4:Ce films of high electrooptical quality by multisource evaporation without post-annealing, using Sr, Ga, S and CeCl3, with addition of an alkali halide. The growth conditions of green-emitting electroluminescent SrGa2S4:Eu thin films by reactive sputtering have been investigated in detail.
Two classes of phosphor materials
- the alkaline earth chalcogenides (AEC), including some ternary compounds, and
- amorphous silicon carbon alloys, hydrogenated, a-SiC:H,
will be systematically studied, taking into account codoping effects. Special attention will be paid to the needs of thin film elecroluminescence, but cathodoluminescence properties will play and important part. Primary preparation of the AEC will be by solid state reaction, to produce powder, which will be investigated under photo- and cathodo-excitation. From the most suitable samples for thin film electroluminescence testing will be prepared by rf- sputtering. For some of the materials nothing is known about the high field transport properties of electrons, and the mechanism of electroluminescence in a-SiC:H is not well understood in general. Basic knowledge has to be obtained, to establish estimates and margins for the efficiency.
The consortium consists of laboratories, having highly specialised experiences and skills, so that a big synergetic effect is expected from the cooperation in a field, in which activities are at present concentrated outside Europe.
Funding SchemeCSC - Cost-sharing contracts