Low-temperature formation of nanocrystalline SiC particles and composite from three-layer Si/C/Si film for the novel enhanced white photoluminescence

In this article, nanocrystalline silicon carbide (nc-SiC) and composite have been synthesized at an annealing temperature as low as 750 °C through the thermal reaction of Si/C/Si multilayers deposited on the Si(100) substrate by ultra-high-vacuum ion beam sputtering (UHV IBS) compared with the conventional thermal formation of crystalline SiC (c-SiC) nanostructures above 1,000 °C. The evolution of microstructure and reaction between C and Si was examined by Raman spectroscopy, Fourier transform infrared spectrometer (FTIR), high-resolution field emission scanning electron microscope (HR-FESEM), and high-resolution transmission electron microscopy. The c-SiC nanoparticles (np-SiC) of around 20-120 nm in diameter appeared on the top and bottom of the three-layer film with a particle density of around 2.63 × 10¹⁰ cm^-2 after 750 °C annealing. The composite of nc-SiC and Si nanocrystals (nc-Si) size below 5 nm embedded in an amorphous SiC (a-SiC) matrix appeared at the interface between the Si and C layers. Efficient thermal energy is the driving force for the formation of nc-SiC and composite through interdiffusion between C and Si. The broad visible photoluminescence (PL) spectrum of 350-750 nm can be obtained from the annealed composite Si/C/Si multilayer and deconvoluted into four bands of blue (∼430 nm), green (∼500 nm), green-yellow (∼550 nm), and orange (∼640 nm) emission, corresponding to the emission origins from nc-SiC, sp² carbon clusters, np-SiC, and nc-Si, respectively.