Optical properties of Si nanocrystals self-nucleated onto SiO2 surfaces

Abstract

SiO₂/Si heterolayers were synthesized employing a RF magnetron sputtering system. For thin Si layers, it is shown that intrinsic voids on the SiO₂ surface act as nucleation sites, promoting the formation of nanocrystals (NCs). As the deposition time of the Si layer increases it is observed that the influence of the SiO₂ texture on the nucleation of Si nanocrystals diminishes. Studies carried out on samples grew on glass substrates shown that control in the NCs sizes allows to control the absorption edges of the synthesized samples between 300 and 700 nm. As-growth samples shown two photoluminescence bands around 570 and 660 nm, a band in the infrared region shows up and shifts toward the visible region as the Si layer thickness decreases.