ELECTRON-PARAMAGNETIC-RESONANCE INVESTIGATION OF SRS-CE POWDERS AND THIN-FILMS

The electron paramagnetic resonance (EPR) of cerium and manganese impu rities has been studied in SrS powders and thin-film electroluminescen t devices (TFELD) containing an SrS luminescent layer. In both types o f material the EPR signal at g =1.31 was attributed to the Ce3+ charge state. A variation of the g value, larger linewidth, and variation of the line shape in the case of TFELD samples are due to larger strains compared to the powders. The spectrum of Mn2+ has been observed in th e SrS:Ce powders and in the intentionally doped SrS:Ce,Mn layers. Cont rary to the undisturbed octahedral behavior of the Mn2+ centre in the powders, an additional axial distortion oriented in the growing direct ion of the layer was found in the TFELD structures. (C) 1996 American Institute of Physics.