Porous silicon dielectric multilayers and microcavities

With recent developments in communication systems and computer technology, the substitution of electrons with photons in data transmission and elaboration has become increasingly attractive. A complete new field of research and technology has born, named photonics, which aims to use photons as information carriers. A great drawback is the fact that silicon, the basic material for microelectronics, is an indirect-gap semiconductor which emits light in the infrared and at very low efficiencies. Thus, one of the main directions of research in photonics is to develop Si-based materials which emit light in the visible range efficiently and predictably: light-emitting Si devices would in fact be cheaper than their counterparts made o compound semiconductors, and could also be integrated onto traditional circuits. Such a device would enable photonic and optoelectronic circuitry to be based entirely on Si and would revolutionize VLSI technology since the other required Si-based devices have already been demonstrated. During the 1990s several dramatic progresses towards this goal have been made by using different materials (Si nanocrystals, porous Si, Si / Ge alloys and superlattices, Er-doped Si, Si / SiO2 superlattices, etc.). A microphotonics entirely based on Si can now be envisaged