Microstructure and atomic effects on the electroluminescent efficiency of SrS:Ce thin film devices

Transmission electron microscopy and x-ray diffraction data show that rapid thermal anneals of SrS:Ce thin films enhance grain size and reduce crystalline defects. Electron paramagnetic resonance results suggest that these anneals lead to less variance in the crystal field environments at the nearly cubic Ce3+ sites along with the formation of another type of Ce3+ sire believed to involve a nearby Sr vacancy. We suggest that the association of Ce3+ sites with V-Sr shifts the electroluminescence towards larger wavelengths as the symmetry of the activator sire is lowered. (C) 1997 American Institute of Physics.