Optical transition in discrete levels of Si quantum dots

Photoluminescence (PL) measurements have been carried out on Si quantum dots (QDs) with sizes of 2–4 nm embedded in Si oxide films. Conspicuous multiple PL peaks separated in energy by up to 104 meV are observed and attributed to optical transitions in discrete energy levels of Si QDs. A band-mixing model of direct and indirect gaps in a nanometer environment consisting of nc-Si core and SiOx surface layer has been proposed for calculation of electronic states. Good agreement is achieved between the observed PL peaks and calculated results. This work provides a path for realizing Si QD laser.