Porous silicon – what is responsible for the visible luminescence?

Abstract
Size‐dependent quantum confinement effects have been invoked to explain the occurrence of vislble luminescence in porous silicon and TEM data supports the existence of crystalline Si domains which have dimensions small enough that one could expect such phenomena. However, is this the whole story? Various proposed explanations are discussed, and the recent observations of luminenscence in Si colloidal suspensions examined.