Visible light emission in porous silicon is of current interest both s
cientifically and technologically. Since this system can exhibit a wid
e variety of structures and particle sizes, however, a large volume of
data exists, which at times can be quite contradictory. In this paper
, a review of the general properties of porous silicon that have been
reported thus far will be given, along with a discussion of the possib
le mechanisms for the luminescence process. The model of quantum confi
nement, amorphous silicon luminescence, a polysilane mechanism and the
siloxene model will be discussed, along with the support for and draw
backs of each particular model.