Effects of interfacial barrier confinement and interfacial states on the light emission of si nanocrystals

The light emission of Si nanocrystal (Si-nc) depends not only on the Si-nc itself, but also on the interface between Si-nc and its matrix. However, systematic reports on the interfacial effects are rare. In this work, we investigate two interfacial effects, i.e., the effect of interfacial barrier confinement and that of interfacial states, on the photoluminescence (PL) of Si-nc in a systematic manner via designing Si-nc samples with different matrices composed of SiO2 or/and Si3N4, and monitoring their PL emissions as functions of exciting photon wavelengths, combined with electron occupation probability calculations. Our results demonstrate that both interfacial effects affect strongly the PL emission of Si-nc. Interfacial states favorable and unfavorable for light emission are also examined. The conclusions drawn from the PL studies also hold for the electroluminescence (EL) of Si-nc, and the interfacial effects should be a major concern for the EL of Si-nc in addition to the carrier transfer.