RAMAN-STUDY OF THE RELATIONSHIP BETWEEN NANOPARTICLES AND PHOTOLUMINESCENCE IN SPARK-PROCESSED SILICON

Spark-processed silicon (sp-Si) that strongly photoluminesces (PL) in the blue and green regions of the visible spectrum has been analyzed b y Raman scattering, in order to probe a possible relationship between the presence and size of Si nanoparticles and PL emission wavelengths. Spatially resolved Raman spectra were measured across spark-processed regions, scanning areas which vary in PL intensity but not wavelength . The observed small shifts and broadenings of the Raman signals indic ate the presence of Si particles having diameters of about 15 nm in th e central, photoluminescing section of the sp region. Slightly smaller Si crystallites with sizes of about 8-9 nm were found in the halo reg ion which does not contribute to FL. Furthermore, the Raman peak shift s and broadenings are essentially identical for blue and green photolu minescing sp-Si. These results suggest that the PL of sp-Si is not cau sed by a quantum-size effect which is coupled to the presence of Si na noparticles. (C) 1997 American Institute of Physics.