Encapsulated semiconductor nanocrystals formed in insulators by ion beam synthesis

Abstract

Both elemental and compound semiconductor nanocrystals have been formed in insulators by ion beam synthesis. Si nanocrystals in SiO 2 give rise to strong optical absorption and intense photoluminescence (PL). The dose dependence of optical absorption provides evidence for size dependent changes in the Si nanocrystal bandgap due to quantum confinement, but the PL results suggest that surface or defect states play an important role in PL. CdS and CdSe nanocrystals have been formed in SiO 2 and in Al 2O 3. Their structure, size, and optical properties are discussed.