Francesco Priolo

Influence of the matrix properties on the performances of Er-doped Si nanoclusters light emitting devices

We investigated the properties of light emitting devices whose active layer consists of Er-doped Si nanoclusters (nc) generated by thermal annealing of Er-doped SiOx layers prepared by magnetron cosputtering. Differently from a widely used technique such as plasma enhanced chemical vapor deposition, sputtering allows to synthesize Er-doped Si nc embedded in an almost stoichiometric oxide matrix, so as to deeply influence the electroluminescence properties of the devices. Relevant results include the need for an unexpected low Si excess for optimizing the device efficiency and, above all, the strong reduction of the influence of Auger de-excitation, which represents the main nonradiative path which limits the performances of such devices and their application in silicon nanophotonics.

Light Emission of Er3+ in Silicon

The introduction of Er impurities in Si would in principle allow electronic excitation of the 4f transition through a carrier-mediated process with a subsequent radiative de-excitation. Indeed, the first Er-doped light emitting diode (LED) operating at 1.54 μm and at 77 K was demonstrated in 1985. However, the achievement of room temperature operation has been hampered for a long time by a strong temperature quenching of the Er luminescence. Important potential applications have driven worldwide an increasing interest in the understanding of the Si:Er system and we have now gained a huge amount of information leading to the fabrication of room temperature operating LEDs described in this chapter.