In this paper the performances of room temperature operating light emitting diodes (LEDs), fabricated by Er ion implantation of crystalline silicon, are investigated in detail. It is shown that 1.54 μm emission is observed under both forward and reverse bias operation, with a much higher intensity under reverse bias. The excitation mechanisms of Er3+ are demonstrated to be very different in the two cases: under forward bias Er is excited through the electron - hole recombination at an Er - related level, while under reverse bias impact excitation by hot carriers represents the excitation process. This last mechanism is shown to occur with a cross section of 6 × 10−17 cm2 and population inversion of the excitable Er sites within the depletion region is demonstrated. The efficiency and limitations of this approach are also discussed.

We report on the excitation and de-excitation processes of erbium implanted in silicon and the integration of Si:Er light emitting devices (LED) with standard CMOS technology. We find two deexcitation processes, an Auger process below 100 K and a phonon mediated energy backtransfer above 100 K. We present the first optical voice link with a silicon LED as the emitter. Optical transmission system performance with our LED is possible below 200 K.

Photo- and electroluminescence were studied in erbium-doped amorphous hydrogenated silicon films. A mechanism of excitation of erbium ions by defect-related Auger process is proposed which permits to explain consistently the whole set of our experimental results.

It is demonstrated room-temperature electroluminescence at 1.54 μm in erbiumimplanted oxygen doped silicon (27 at. 0), due to intra-4f transitions of the Er3+. The luminescence is electrically stimulated by biasing metal-(Si:O,Er)-p+ silicon diodes. The 30 nm thick Si:O,Er films are amorphous layers deposited onto silicon substrates by chemical vapour deposition of SiH4 and N20, doped by ion implantation with Er to a concentration up to ≈ 1.5 at.%, and annealed in a rapid thermal annealing furnace. The most intense electroluminescence is obtained in samples annealed at 400°C in reverse bias under breakdown condition and it is attributed to impact excitation of erbium by hot carriers injected from the Si into the Si:O,Er layer. The electrical characteristics of the diode are studied in detail and related to the electroluminescence characteristics. A lower limit for the impact excitation cross-section of ≈6×10−16 cm2 is obtained.

Photoluminescence in the neighborhood of 1.54μm due to the 4I13/2 → 4l15/2 transitions is observed from 2 K up to 520 K in erbium implanted 6H SiC. The integrated 1.54 μm photoluminescence (PL) intensity is almost constant from 2 K up to about 400 K, with slight sample to sample variation. The shallow nitrogen donors play an important role in the excitation of the Er3+ centers. 1.54 μm electroluminescence (EL) is observed in erbium implanted 6H SiC p-n junctions under forward bias conditions. The EL spectrum is identical to the PL spectrum.

Er-doped GaP diodes that exhibit strong room temperature characteristic 4f-shell luminescence under forward bias have been fabricated. The output of the diode increases linearly with current for low current densities but eventually saturates. The radiative decay lifetime is 2.6 msec and is independent of current. It is proposed that the observed intensity dependence on excitation power results from saturation of the optically active Er3+ centers. Some diodes showed a superlinear dependence, with a threshold of about 2 A/cm2.

Nd-doped semiconductor light-emitting diodes were fabricated by implanting Nd ions into a GaAs epi-layer. The fabricated GaAs:Nd diodes show good current-voltage characteristics with a typical reverse breakdown voltage between 8 and 12 V By injecting minority carriers into the diodes, Nd3+ related emissions were observed, at 77 K, in the 0.92, 1.11, and 1.3 μm regions. These electroluminescence signals correspond to the transitions from Nd3+4F3/2 state to the Nd3+4I9/2, 4I1/2, and 4I13/2 states, respectively. The measured external quantum efficiency of the GaAs:Nd diodes at 77 K, was 5 × 10−7.

Rare earth (Gd, Eu, Er) doped InGaAs and InP layers were grown by liquid phase epitaxy (LPE). The refractive index of these layers was observed to increase with the addition of the rare earth ions. The observed increase could not be explained by changes in host composition as typically calculated from changes in lattice parameter. In fact, the refractive index was seen to increase (∼0.25) by an order of magnitude more than would be expected by the change in the lattice parameter (∼0.02). The increased refractive indices of InP layers due to Er-doping enabled waveguiding. These findings suggest that optically active waveguide devices can be fabricated from semiconducting hosts by simple rare earth doping.