SOME NEW ASPECTS OF POROUS SILICON

We recall the geometry of porous silicon and the order of magnitude of some characteristic parameters. We give a brief review of optical exp eriments and their different interpretations. We focus on quantitative interpretations and show that an essential concept is confinement in a quantum wire or box. In particular, the exchange energy of electron- hole pairs correlated by Coulomb interaction inside a quantum box expl ains results obtained between 4 K and room temperature. Nevertheless, the large shift of the main luminescence line for similar porous silic on but different electrolytes cannot be explained by quantum confineme nt alone and has to be accounted for by the difference between the die lectric constants inside and outside the porous silicon. A brief accou nt of electroluminescence experiments is also given.