Optical properties of nano-silicon

We investigated the optical properties of silicon clusters and Si nanocryst allites using photoluminescence (PL) and Raman scattering technique, Broad luminescence band in the red region was observed from Si-doped SiO2 thin fi lms deposited by co-sputtering of Si and SiO2 on p-type Si (100) substrates , annealed in Ar and O-2 atmosphere. Nanocrystalline Si particles fabricate d by pulsed plasma processing technique showed infrared luminescence from a s grown him at room temperature. Raman spectra from these Olms consisted of broad band superimposed on a sharp line near 516 cm(-1) whose intensity, f requency, and width depend on the particle sizes arising from the phonon co nfinement in the nanocrystalline silicon. We also performed FL, Raman and r esonantly excited PL measurements on porous silicon film to compare the opt ical properties of Si nanostructures grown by different techniques. An exte nsive computer simulation using empirical pseudopotential method was carrie d out Tor 5-18 atoms Si clusters and the calculated gap energies were close to our PL data.