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.
The electrical and optical properties of MBE grown Europium doped CaF2 layers onp‐ type Silicon (100) substrates reveal the possibility of using this materials system to fabricate light emitters on silicon. Low temperature MBE growth of the Eu:CaF2 layers permits the incorporation of up to 7.48 atomic weight % Eu in the epilayer without causing significant degradation of the layer ciystallinity. Strong room temperature photoluminescence in the blue‐violet spectral range has been observed in these samples, without any luminescence quenching even when the Eu concentration in the CaF2 epilayer is as high as 7.48 atomic weight percent. The current versus voltage data reveal that high current densities can be sustained through the Eu:CaF2 epilayers without causing catastrophic failure of the dielectric layer. Visible DC electroluminescence (EL) is observed by injecting electrons into Eu2+ doped CaF2 layers. High current densities up to ~50A/cm2 have been sustained through these materials with a DC bias of ~30 volts.
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