IDENTITY OF THE LIGHT-EMITTING STATES IN POROUS SILICON WIRES

We present empirical pseudopotential calculations of the electronic st ructure of [001] silicon quantum wires, aiming at identification of th e states that couple radiatively to the valence-band maximum. We find that the near-gap wave functions differ qualitatively from effective-m ass depictions. Instead, they can be described as off-GAMMA bulk state s. The effects of H chemisorption on the wire energies and wave functi ons are studied. We find that the Si skeleton dominates the emission. The resulting lifetimes versus energy relation agrees with the experim ental measurements only if one assumes coexistence of quantum wires wi th quantum dots.