Mid-infrared (3.5 ?m) electroluminescence from heavily Fe2+ ion-implanted semi-insulating InP

We report the observation of efficient mid-infrared electroluminescence associated with internal transitions of Fe2+ deep levels in overcompensated n-type InP:Fe, ion implanted with Fe doses in the range 1013-1015 cm-2. Unprecedented high active Fe2+ densities up to ∼1018 cm-3 are obtained with a combination of high temperature implantation and annealing procedure. The characteristic spectrum of Fe2+, dominated by a set of sharp lines corresponding to the symmetry allowed d-shell transitions, can be observed up to 30 K. A broader emission is detectable up to 200 K. The estimated conversion efficiency of electrical into mid-infrared optical power is ∼5 × 10-5, a factor of ∼50 larger than previously reported value in MOCVD-grown planar electroluminescent devices.