Visible Electoluminescence from Eu:CaF₂ Layers on Si
Top right shows a schematic of the Electroluminescence device. Bottom right show the Electroluminescence spectra. The optical photograph to the left shows visible light from a single device on a 5 mm by 5 mm sample.


Visible electroluminescence (EL) is observed at room temperature by current injection into Eu:CaF₂ layers containing 7.5 and 8.0 at. % Eu grown by molecular beam epitaxy on lightly doped (100) p-type silicon. The EL spectra are broad with peaks near 700 and 600 nm, respectively. Room temperature photoluminescence spectra for the same samples exhibited peaks near 420 nm, with higher doped samples showing a more pronounced long wavelength tail. Although both metal and indium–tin–oxide (ITO) contacts were successfully used for current injection, the best EL intensity stability was achieved with contacts made of a 100 Å thick Al layer covered by a 2500 Å thick ITO layer. © 1997 American Institute of Physics.