Intrinsic band-edge photoluminescence from silicon clusters at room temperature

Abstract
We report silicon band-edge photoluminescence (PL) with photon energy of 1.1 eV and external quantum efficiency (EQE) better than 103 in samples prepared by high-temperature oxidation of porous silicon. The integrated PL intensity is insensitive to temperature. The EQE strongly depends on the annealing conditions: temperature, time, and ambient. A model is proposed in which the PL originates from silicon clusters within a nonstoichiometric silicon-rich silicon oxide matrix.