Thermal evaporation synthesis of SiC/SiOx nanochain heterojunctions and their photoluminescence properties

Abstract

Core–shell SiC/SiO_x nanochain heterojunctions have been successfully synthesized on silicon substrate via a simplified thermal evaporation method at 1500 °C without using catalyst, template or flowing gases (Ar, CH₄, N₂, etc.). X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy and Fourier-transform infrared spectroscopy are used to characterize the phase composition, morphology, and microstructure of the as-synthesized nanostructures. A combined vapor–solid growth and modulation procedure is proposed for the growth mode of the as-grown SiC/SiO_x nanochains. The formation of SiO_x beads not only relates to the Rayleigh instability and the poor wettability between SiC and SiO_x, but also to the existence of a high density of stacking faults within SiC-core nanowires. The photoluminescence spectrum of the nanochains exhibits a significant blue shift, which can be highly valuable for future potential applications in blue-green emitting devices.