Enhancement of the core near-band-edge emission induced by an amorphous shell in coaxial one-dimensional nanostructure: the case of SiC/SiO2 core/shell self-organized nanowires

We report the influence of the native amorphous SiO2 shell on the cathodoluminescence emission of 3C-SiC/SiO2 core/shell nanowires. A shell-induced enhancement of the SiC near-band-edge emission is observed and studied as a function of the silicon dioxide thickness. Since the diameter of the investigated SiC cores rules out any direct bandgap optical transitions due to confinement effects, this enhancement is ascribed to a carrier diffusion from the shell to the core, promoted by the alignment of the SiO2 and SiC bands in a type I quantum well. An accurate correlation between the optical emission and structural and SiO2-SiC interface properties is also reported.