Exciton-light coupling and polaritons in SiC nanocrystals

The paper presents the results of SiC:N nanocrystal characterization using the photoluminescence (PL) and X-ray diffraction (XRD) techniques. Photoluminescence study of porous SiC:N (PSiC) layers with different PSiC thicknesses and SiC nanocrystal (NC) sizes reveals the intensity stimulation mainly for the high energy PL bands. The early investigation of temperature dependences of the high energy PL bands has shown that these PL bands related to the free exciton emission in the different SiC polytypes. The SiC polytypes in the original n-type SiC:N wafers and in porous SiC layers were confirmed by XRD study. The intensity enhancement of exciton-related PL bands in big size (50–250 nm) SiC NCs is attributed to the realization of the exciton week confinement and exciton-light coupling with the formation of polaritons in the SiC NCs. The numerical simulation of exciton radiative recombination rates and radiative lifetimes for the different exciton emissions has been done using a model of exciton–light coupling in SiC NCs. The experimental and numerically calculated results have been compared and discussed.

► The stimulation of PL intensity in SiC:N nanocrystals has been detected.
► PL enhancement is attributed to exciton–light coupling in SiC NCs.
► Recombination rates and lifetime were calculated for the exciton–light coupling model.
► The carbon amorphous phase is detected by XRD in the high porosity SiC.
► Low energy PL bands are assigned to the defects deal with carbon interstitials.