Growth and visible photoluminescence of SiCxNy/AlN nanoparticle superlattices

Luminescent SiCxNy/AlN nanoparticle superlattices (NPSLs) were fabricated by sputtering SiC and Al targets alternatively under a mixture gaseous flow of N2, Ar, and H2 by plasma RF magnetron sputtering. It was found that the best periodic structures and greatest content of SiCxNy nanoparticles occur in the case in which the sublayer thickness of SiCxNy and AlN are 42 and 3 nm, respectively. In this case, the NPSLs exhibit strong photoluminescence (PL) either before or after annealing. Annealing at different temperature (Tanneal) revealed that the PL intensity first increases with increasing Tanneal and PL peak is red-shifted when Tanneal>650 °C; the PL intensity reaches a maximum as Tanneal=1100 °C. A microstructure model that takes into account the formation energy of SiCxNy nanocrystal limited by AlN sublayers was developed to tentatively explain the formation of SiCxNy nanocrystal in SiCxNy/AlN NPSLs. Based on the structural analysis by X-ray diffraction and Fourier-transform infrared spectra, the PL of SiCxNy/AlN NPSLs was discussed.