Strong and stable visible luminescence from Au-passivated porous silicon

We report on porous silicon (PS) samples with strong and stable red photoluminescence (PL) prepared by chemical anodization of gold-plated substrate. We demonstrate that the structural stability of Au-passivated porous silicon is much better than that of normal PS. It is also found that the PL intensity of Au-passivated PS can be enhanced by a factor of 3 when prepared under the same condition as that for normal PS. The infrared absorption spectra reveal that the photoluminescence stability can be attributed to the formation of stable Au–Si bonds on the surface of porous silicon. In addition, our study provides further evidence to support the quantum confinement model of the red emission of porous silicon.