Luminescence

In the early 1990s, L. T. Canham at the Royal Signal and Radar Establishment in England reported luminescence from porous silicon. This generated great interest, because if the luminescence could be controlled, then light-emitting devices could be integrated with silicon microelectronics. Although silicon photodetectors had been made, the material had not been known to emit light before. This could lead the way to relatively inexpensive optical computers, signal-processing devices, and optical communications devices.

Debate about what process creates the light is divided: those who believe the light is emitted as part of a quantum confinement effect and those who believe that the light is the product of a chemical reaction between the silicon and oxygen. If the quantum confinement theory proves correct and the effect can be prolonged, then useful light-emitting devices could be made from porous silicon. If the chemical theory is correct, then the luminescent period is probably inherently short-lived and the material would not make good reusable devices. Although no one has published reports that definitely debunk one theory, the chemical theory is most popular at the moment because of the instability of porous silicon devices.