Composite rods based on nanoscale porous silicon in sol–gel silica and ormosil matrices for light-emitting applications

In this paper, we report a new approach for fabrication of porous silicon (PSi) composites sol–gel-based matrix rods. PSi colloidal solutions were directly encapsulated in two types of sols prepared by the sol–gel process. The property of nanocomposite silica and ormosil matrix was investigated by optical techniques. Absorption and its band gap of PSi in silica and ormosils are influenced by matrix environment. Emission properties of PSi are affected by the surrounding matrix and temperature. The morphology of nanocomposites was characterized by scanning electron microscopy, indicating the dissimilar surface structure of the PSi in the matrix. The PSi particles in the matrices are well distributed with more or less 5–8 nm size as confirmed by transmission electron microscopy. Crack-free PSi composite silica and ormosil-based rods were successfully developed. The cutting and polishing of the surface of rods was performed. Subsequently, spontaneous emission of the rods was examined using a high pico second 355 nm laser source. The enhanced emission from the nanocomposite ormosils is remarkable and more prominent than the nanocomposite silica rod. Such typical spontaneous emission from nanocomposite rods indicates that it may be possible to improve if highly dense PSi colloidal solution is used. The present results are of benefit in further understanding more about the photoluminescence mechanism of PSi in the matrices.