We describe here a new technology, dislocation engineering, and in particular how this approach, when incorporated appropriately in to a p–n junction, can add the new functionality of efficient electroluminescence at room temperature from silicon-based light emitting devices. Simple (undoped) silicon devices emit at 1.15 μm, at the Si band gap energy. In this paper, we show how emission at other wavelengths, such as 1.3 and 1.5 μm, can be achieved by doping a standard dislocation engineered light emitting device with an appropriate optical centre, such as sulphur and erbium.