Excitation mechanisms and light emitting device performances in Er-doped crystalline Si

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.