The mechanism of formation and photoluminescence of Si quantum dots embedded in amorphous SiO_2 matrix

摘要

Films of a-SiO_x with different oxygen content were deposited by electron cyclotron resonance (ECR) microwave plasma technique at toom temperature, where the films were annealed in an Ar ambient for 30 minutes at temperatures range from 250 to 1050 deg C. The system of nc-Si quantum dots (QDs) dispersed in SiO_2 matrix was obtained for the films annealed at 1050 deg C. The structural change induced from annealing was characterized by infrared and Raman spectra, which was correlated with the identification of luminescence centers. A broad photoluminescence band centered at 750 to 770 nm is attributed to the quantum confinement effect (QCE) of the Si clusters. another PL band between 560-620 nm is attributed to the defects in the interfacial regions: self-trapped excitons.